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From: "yunfeng zhang" <zyf.zeroos@gmail.com>
To: linux-kernel@vger.kernel.org
Subject: [PATCH 2.6.16.29 1/1] memory: enhance Linux swap subsystem
Date: Tue, 26 Dec 2006 16:18:32 +0800	[thread overview]
Message-ID: <4df04b840612260018u4be268cod9886edefd25c3a@mail.gmail.com> (raw)

In the patch, I introduce a new page system -- pps which can improve
Linux swap subsystem performance, you can find a new document in
Documentation/vm_pps.txt. In brief, swap subsystem should scan/reclaim
pages on VMA instead of zone::active list ...

--- patch-linux/fs/exec.c	2006-12-26 15:20:02.683546016 +0800
+++ linux-2.6.16.29/fs/exec.c	2006-09-13 02:02:10.000000000 +0800
@@ -323,0 +324 @@
+	lru_cache_add_active(page);
@@ -438 +438,0 @@
-		enter_pps(mm, mpnt);
--- patch-linux/mm/swap_state.c	2006-12-26 15:20:02.689545104 +0800
+++ linux-2.6.16.29/mm/swap_state.c	2006-09-13 02:02:10.000000000 +0800
@@ -357,2 +357 @@
-			if (vma == NULL || !(vma->vm_flags & VM_PURE_PRIVATE))
-				lru_cache_add_active(new_page);
+			lru_cache_add_active(new_page);
--- patch-linux/mm/mmap.c	2006-12-26 15:20:02.691544800 +0800
+++ linux-2.6.16.29/mm/mmap.c	2006-09-13 02:02:10.000000000 +0800
@@ -209 +208,0 @@
-	leave_pps(vma, 0);
@@ -597 +595,0 @@
-		leave_pps(next, 0);
@@ -1096,2 +1093,0 @@
-	enter_pps(mm, vma);
-
@@ -1120 +1115,0 @@
-		leave_pps(vma, 0);
@@ -1148 +1142,0 @@
-	leave_pps(vma, 0);
@@ -1726,4 +1719,0 @@
-	if (new->vm_flags & VM_PURE_PRIVATE) {
-		new->vm_flags &= ~VM_PURE_PRIVATE;
-		enter_pps(mm, new);
-	}
@@ -1930 +1919,0 @@
-	enter_pps(mm, vma);
@@ -2054,4 +2042,0 @@
-			if (new_vma->vm_flags & VM_PURE_PRIVATE) {
-				new_vma->vm_flags &= ~VM_PURE_PRIVATE;
-				enter_pps(mm, new_vma);
-			}
--- patch-linux/mm/fremap.c	2006-12-26 15:20:02.695544192 +0800
+++ linux-2.6.16.29/mm/fremap.c	2006-09-13 02:02:10.000000000 +0800
@@ -40 +40 @@
-		if (pte_swapped(pte))
+		if (!pte_file(pte))
--- patch-linux/mm/rmap.c	2006-12-26 15:20:02.696544040 +0800
+++ linux-2.6.16.29/mm/rmap.c	2006-09-13 02:02:10.000000000 +0800
@@ -636 +636 @@
-		BUG_ON(!pte_swapped(*pte));
+		BUG_ON(pte_file(*pte));
--- patch-linux/mm/vmscan.c	2006-12-26 15:20:02.697543888 +0800
+++ linux-2.6.16.29/mm/vmscan.c	2006-09-13 02:02:10.000000000 +0800
@@ -1517,392 +1516,0 @@
-struct series_t {
-	pte_t orig_ptes[MAX_SERIES_LENGTH];
-	pte_t* ptes[MAX_SERIES_LENGTH];
-	struct page* pages[MAX_SERIES_LENGTH];
-	int series_length;
-	int series_stage;
-} series;
-
-static int get_series_stage(pte_t* pte, int index)
-{
-	series.orig_ptes[index] = *pte;
-	series.ptes[index] = pte;
-	if (pte_present(series.orig_ptes[index])) {
-		struct page* page = pfn_to_page(pte_pfn(series.orig_ptes[index]));
-		series.pages[index] = page;
-		if (page == ZERO_PAGE(addr)) // reserved page is exclusive from us.
-			return 7;
-		if (pte_young(series.orig_ptes[index])) {
-			return 1;
-		} else
-			return 2;
-	} else if (pte_unmapped(series.orig_ptes[index])) {
-		struct page* page = pfn_to_page(pte_pfn(series.orig_ptes[index]));
-		series.pages[index] = page;
-		if (!PageSwapCache(page))
-			return 3;
-		else {
-			if (PageWriteback(page) || PageDirty(page))
-				return 4;
-			else
-				return 5;
-		}
-	} else // pte_swapped -- SwappedPTE
-		return 6;
-}
-
-static void find_series(pte_t** start, unsigned long* addr, unsigned long end)
-{
-	int i;
-	int series_stage = get_series_stage((*start)++, 0);
-	*addr += PAGE_SIZE;
-
-	for (i = 1; i < MAX_SERIES_LENGTH && *addr < end; i++, (*start)++,
*addr += PAGE_SIZE) {
-		if (series_stage != get_series_stage(*start, i))
-			break;
-	}
-	series.series_stage = series_stage;
-	series.series_length = i;
-}
-
-struct delay_tlb_task_t delay_tlb_tasks[32] = { [0 ... 31] = {0} };
-
-void timer_flush_tlb_tasks(void* data)
-{
-	// To x86, if we found there were some flushing tasks, we should do
it all together, that is, flush it once.
-	int i;
-#ifdef CONFIG_X86
-	int flag = 0;
-#endif
-	for (i = 0; i < 32; i++) {
-		if (delay_tlb_tasks[i].mm != NULL &&
-				cpu_isset(smp_processor_id(), delay_tlb_tasks[i].mm->cpu_vm_mask) &&
-				cpu_isset(smp_processor_id(), delay_tlb_tasks[i].cpu_mask)) {
-#ifdef CONFIG_X86
-			flag = 1;
-#elif
-			// smp::local_flush_tlb_range(delay_tlb_tasks[i]);
-#endif
-			cpu_clear(smp_processor_id(), delay_tlb_tasks[i].cpu_mask);
-		}
-	}
-#ifdef CONFIG_X86
-	if (flag)
-		local_flush_tlb();
-#endif
-}
-
-static struct delay_tlb_task_t* delay_task = NULL;
-static int vma_index = 0;
-
-static struct delay_tlb_task_t* search_free_tlb_tasks_slot(void)
-{
-	struct delay_tlb_task_t* ret = NULL;
-	int i;
-again:
-	for (i = 0; i < 32; i++) {
-		if (delay_tlb_tasks[i].mm != NULL) {
-			if (cpus_empty(delay_tlb_tasks[i].cpu_mask)) {
-				mmput(delay_tlb_tasks[i].mm);
-				delay_tlb_tasks[i].mm = NULL;
-				ret = &delay_tlb_tasks[i];
-			}
-		} else
-			ret = &delay_tlb_tasks[i];
-	}
-	if (!ret) { // Force flush TLBs.
-		on_each_cpu(timer_flush_tlb_tasks, NULL, 0, 1);
-		goto again;
-	}
-	return ret;
-}
-
-static void init_delay_task(struct mm_struct* mm)
-{
-	cpus_clear(delay_task->cpu_mask);
-	vma_index = 0;
-	delay_task->mm = mm;
-}
-
-/*
- * We will be working on the mm, so let's force to flush it if necessary.
- */
-static void start_tlb_tasks(struct mm_struct* mm)
-{
-	int i, flag = 0;
-again:
-	for (i = 0; i < 32; i++) {
-		if (delay_tlb_tasks[i].mm == mm) {
-			if (cpus_empty(delay_tlb_tasks[i].cpu_mask)) {
-				mmput(delay_tlb_tasks[i].mm);
-				delay_tlb_tasks[i].mm = NULL;
-			} else
-				flag = 1;
-		}
-	}
-	if (flag) { // Force flush TLBs.
-		on_each_cpu(timer_flush_tlb_tasks, NULL, 0, 1);
-		goto again;
-	}
-	BUG_ON(delay_task != NULL);
-	delay_task = search_free_tlb_tasks_slot();
-	init_delay_task(mm);
-}
-
-static void end_tlb_tasks(void)
-{
-	if (!cpus_empty(delay_task->cpu_mask)) {
-		atomic_inc(&delay_task->mm->mm_users);
-		delay_task->cpu_mask = delay_task->mm->cpu_vm_mask;
-	} else
-		delay_task->mm = NULL;
-	delay_task = NULL;
-}
-
-static void fill_in_tlb_tasks(struct vm_area_struct* vma, unsigned long addr,
-		unsigned long end)
-{
-	struct mm_struct* mm;
-fill_it:
-	if (vma_index != 32) {
-		delay_task->vma[vma_index] = vma;
-		delay_task->start[vma_index] = addr;
-		delay_task->end[vma_index] = end;
-		vma_index++;
-		return;
-	}
-	mm = delay_task->mm;
-	end_tlb_tasks();
-
-	delay_task = search_free_tlb_tasks_slot();
-	init_delay_task(mm);
-	goto fill_it;
-}
-
-static void shrink_pvma_scan_ptes(struct scan_control* sc,
-		struct mm_struct* mm, struct vm_area_struct* vma, pmd_t* pmd,
-		unsigned long addr, unsigned long end)
-{
-	int i;
-	spinlock_t* ptl = pte_lockptr(mm, pmd);
-	pte_t* pte = pte_offset_map(pmd, addr);
-	int anon_rss = 0;
-	struct pagevec freed_pvec;
-	int may_enter_fs = (sc->gfp_mask & (__GFP_FS | __GFP_IO));
-	struct address_space* mapping = &swapper_space;
-
-	pagevec_init(&freed_pvec, 1);
-	do {
-		memset(&series, 0, sizeof(struct series_t));
-		find_series(&pte, &addr, end);
-		switch (series.series_stage) {
-			case 1: // PTE -- untouched PTE.
-				for (i = 0; i < series.series_length; i++) {
-					struct page* page = series.pages[i];
-					lock_page(page);
-					spin_lock(ptl);
-					if (unlikely(pte_same(*series.ptes[i], series.orig_ptes[i]))) {
-						if (pte_dirty(*series.ptes[i]))
-							set_page_dirty(page);
-						set_pte_at(mm, addr + i * PAGE_SIZE, series.ptes[i],
-								pte_mkold(pte_mkclean(*series.ptes[i])));
-					}
-					spin_unlock(ptl);
-					unlock_page(page);
-				}
-				fill_in_tlb_tasks(vma, addr, addr + (PAGE_SIZE * series.series_length));
-				break;
-			case 2: // untouched PTE -- UnmappedPTE.
-				/*
-				 * Note in stage 1, we've flushed TLB in fill_in_tlb_tasks, so
-				 * if it's still clear here, we can shift it to Unmapped type.
-				 *
-				 * If some architecture doesn't support atomic cmpxchg
-				 * instruction or can't atomically set the access bit after
-				 * they touch a pte at first, combine stage 1 with stage 2, and
-				 * send IPI immediately in fill_in_tlb_tasks.
-				 */
-				spin_lock(ptl);
-				for (i = 0; i < series.series_length; i++) {
-					if (unlikely(pte_same(*series.ptes[i], series.orig_ptes[i]))) {
-						pte_t pte_unmapped = series.orig_ptes[i];
-						pte_unmapped.pte_low &= ~_PAGE_PRESENT;
-						pte_unmapped.pte_low |= _PAGE_UNMAPPED;
-						if (cmpxchg(&series.ptes[i]->pte_low,
-									series.orig_ptes[i].pte_low,
-									pte_unmapped.pte_low) !=
-								series.orig_ptes[i].pte_low)
-							continue;
-						page_remove_rmap(series.pages[i]);
-						anon_rss--;
-					}
-				}
-				spin_unlock(ptl);
-				break;
-			case 3: // Attach SwapPage to PrivatePage.
-				/*
-				 * A better arithmetic should be applied to Linux SwapDevice to
-				 * allocate fake continual SwapPages which are close to each
-				 * other, the offset between two close SwapPages is less than 8.
-				 */
-				if (sc->may_swap) {
-					for (i = 0; i < series.series_length; i++) {
-						lock_page(series.pages[i]);
-						if (!PageSwapCache(series.pages[i])) {
-							if (!add_to_swap(series.pages[i], GFP_ATOMIC)) {
-								unlock_page(series.pages[i]);
-								break;
-							}
-						}
-						unlock_page(series.pages[i]);
-					}
-				}
-				break;
-			case 4: // SwapPage isn't consistent with PrivatePage.
-				/*
-				 * A mini version pageout().
-				 *
-				 * Current swap space can't commit multiple pages together:(
-				 */
-				if (sc->may_writepage && may_enter_fs) {
-					for (i = 0; i < series.series_length; i++) {
-						struct page* page = series.pages[i];
-						int res;
-
-						if (!may_write_to_queue(mapping->backing_dev_info))
-							break;
-						lock_page(page);
-						if (!PageDirty(page) || PageWriteback(page)) {
-							unlock_page(page);
-							continue;
-						}
-						clear_page_dirty_for_io(page);
-						struct writeback_control wbc = {
-							.sync_mode = WB_SYNC_NONE,
-							.nr_to_write = SWAP_CLUSTER_MAX,
-							.nonblocking = 1,
-							.for_reclaim = 1,
-						};
-						page_cache_get(page);
-						SetPageReclaim(page);
-						res = swap_writepage(page, &wbc);
-						if (res < 0) {
-							handle_write_error(mapping, page, res);
-							ClearPageReclaim(page);
-							page_cache_release(page);
-							break;
-						}
-						if (!PageWriteback(page))
-							ClearPageReclaim(page);
-						page_cache_release(page);
-					}
-				}
-				break;
-			case 5: // UnmappedPTE -- SwappedPTE, reclaim PrivatePage.
-				for (i = 0; i < series.series_length; i++) {
-					struct page* page = series.pages[i];
-					lock_page(page);
-					spin_lock(ptl);
-					if (unlikely(pte_same(*series.ptes[i], series.orig_ptes[i]))) {
-						spin_unlock(ptl);
-						unlock_page(page);
-						continue;
-					}
-					swp_entry_t entry = { .val = page_private(page) };
-					swap_duplicate(entry);
-					pte_t pte_swp = swp_entry_to_pte(entry);
-					set_pte_at(mm, addr + i * PAGE_SIZE, series.ptes[i], pte_swp);
-					spin_unlock(ptl);
-					if (PageSwapCache(page) && !PageWriteback(page))
-						delete_from_swap_cache(page);
-					unlock_page(page);
-
-					if (!pagevec_add(&freed_pvec, page))
-						__pagevec_release_nonlru(&freed_pvec);
-					sc->nr_reclaimed++;
-				}
-				break;
-			case 6:
-				// NULL operation!
-				break;
-		}
-	} while (addr < end);
-	add_mm_counter(mm, anon_rss, anon_rss);
-	if (pagevec_count(&freed_pvec))
-		__pagevec_release_nonlru(&freed_pvec);
-}
-
-static void shrink_pvma_pmd_range(struct scan_control* sc, struct
mm_struct* mm,
-		struct vm_area_struct* vma, pud_t* pud,
-		unsigned long addr, unsigned long end)
-{
-	unsigned long next;
-	pmd_t* pmd = pmd_offset(pud, addr);
-	do {
-		next = pmd_addr_end(addr, end);
-		if (pmd_none_or_clear_bad(pmd))
-			continue;
-		shrink_pvma_scan_ptes(sc, mm, vma, pmd, addr, next);
-	} while (pmd++, addr = next, addr != end);
-}
-
-static void shrink_pvma_pud_range(struct scan_control* sc, struct
mm_struct* mm,
-		struct vm_area_struct* vma, pgd_t* pgd,
-		unsigned long addr, unsigned long end)
-{
-	unsigned long next;
-	pud_t* pud = pud_offset(pgd, addr);
-	do {
-		next = pud_addr_end(addr, end);
-		if (pud_none_or_clear_bad(pud))
-			continue;
-		shrink_pvma_pmd_range(sc, mm, vma, pud, addr, next);
-	} while (pud++, addr = next, addr != end);
-}
-
-static void shrink_pvma_pgd_range(struct scan_control* sc, struct
mm_struct* mm,
-		struct vm_area_struct* vma)
-{
-	unsigned long next;
-	unsigned long addr = vma->vm_start;
-	unsigned long end = vma->vm_end;
-	pgd_t* pgd = pgd_offset(mm, addr);
-	do {
-		next = pgd_addr_end(addr, end);
-		if (pgd_none_or_clear_bad(pgd))
-			continue;
-		shrink_pvma_pud_range(sc, mm, vma, pgd, addr, next);
-	} while (pgd++, addr = next, addr != end);
-}
-
-static void shrink_private_vma(struct scan_control* sc)
-{
-	struct mm_struct* mm;
-	struct vm_area_struct* vma;
-	struct list_head *pos, *lhtemp;
-
-	spin_lock(&mmlist_lock);
-	list_for_each_safe(pos, lhtemp, &init_mm.mmlist) {
-		mm = list_entry(pos, struct mm_struct, mmlist);
-		if (atomic_inc_return(&mm->mm_users) == 1) {
-			atomic_dec(&mm->mm_users);
-			continue;
-		}
-		spin_unlock(&mmlist_lock);
-		start_tlb_tasks(mm);
-		if (down_read_trylock(&mm->mmap_sem)) {
-			for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
-				if (!(vma->vm_flags & VM_PURE_PRIVATE))
-					continue;
-				if (vma->vm_flags & VM_LOCKED)
-					continue;
-				shrink_pvma_pgd_range(sc, mm, vma);
-			}
-			up_read(&mm->mmap_sem);
-		}
-		end_tlb_tasks();
-		mmput(mm);
-		spin_lock(&mmlist_lock);
-	}
-	spin_unlock(&mmlist_lock);
-}
-
@@ -1952 +1559,0 @@
-	shrink_private_vma(&sc);
--- patch-linux/mm/swapfile.c	2006-12-26 15:20:02.699543584 +0800
+++ linux-2.6.16.29/mm/swapfile.c	2006-09-13 02:02:10.000000000 +0800
@@ -10 +9,0 @@
-#include <linux/mm_inline.h>
@@ -421,157 +419,0 @@
-static int pps_test_swap_type(struct mm_struct* mm, pmd_t* pmd, pte_t* pte, int
-		type, struct page** ret_page)
-{
-	spinlock_t* ptl = pte_lockptr(mm, pmd);
-	swp_entry_t entry;
-	struct page* page;
-
-	spin_lock(ptl);
-	if (!pte_present(*pte) && pte_swapped(*pte)) {
-		entry = pte_to_swp_entry(*pte);
-		if (swp_type(entry) == type) {
-			*ret_page = NULL;
-			spin_unlock(ptl);
-			return 1;
-		}
-	} else {
-		page = pfn_to_page(pte_pfn(*pte));
-		if (PageSwapCache(page)) {
-			entry.val = page_private(page);
-			if (swp_type(entry) == type) {
-				page_cache_get(page);
-				*ret_page = page;
-				spin_unlock(ptl);
-				return 1;
-			}
-		}
-	}
-	spin_unlock(ptl);
-	return 0;
-}
-
-static int pps_swapoff_scan_ptes(struct mm_struct* mm, struct vm_area_struct*
-		vma, pmd_t* pmd, unsigned long addr, unsigned long end, int type)
-{
-	pte_t *pte;
-	struct page* page;
-
-	pte = pte_offset_map(pmd, addr);
-	do {
-		while (pps_test_swap_type(mm, pmd, pte, type, &page)) {
-			if (page == NULL) {
-				switch (__handle_mm_fault(mm, vma, addr, 0)) {
-				case VM_FAULT_SIGBUS:
-				case VM_FAULT_OOM:
-					return -ENOMEM;
-				case VM_FAULT_MINOR:
-				case VM_FAULT_MAJOR:
-					break;
-				default:
-					BUG();
-				}
-			} else {
-				wait_on_page_locked(page);
-				wait_on_page_writeback(page);
-				lock_page(page);
-				if (!PageSwapCache(page)) {
-					unlock_page(page);
-					page_cache_release(page);
-					break;
-				}
-				wait_on_page_writeback(page);
-				delete_from_swap_cache(page);
-				unlock_page(page);
-				page_cache_release(page);
-				break;
-			}
-		}
-	} while (pte++, addr += PAGE_SIZE, addr != end);
-	return 0;
-}
-
-static int pps_swapoff_pmd_range(struct mm_struct* mm, struct vm_area_struct*
-		vma, pud_t* pud, unsigned long addr, unsigned long end, int type)
-{
-	unsigned long next;
-	int ret;
-	pmd_t* pmd = pmd_offset(pud, addr);
-	do {
-		next = pmd_addr_end(addr, end);
-		if (pmd_none_or_clear_bad(pmd))
-			continue;
-		ret = pps_swapoff_scan_ptes(mm, vma, pmd, addr, next, type);
-		if (ret == -ENOMEM)
-			return ret;
-	} while (pmd++, addr = next, addr != end);
-	return 0;
-}
-
-static int pps_swapoff_pud_range(struct mm_struct* mm, struct vm_area_struct*
-		vma, pgd_t* pgd, unsigned long addr, unsigned long end, int type)
-{
-	unsigned long next;
-	int ret;
-	pud_t* pud = pud_offset(pgd, addr);
-	do {
-		next = pud_addr_end(addr, end);
-		if (pud_none_or_clear_bad(pud))
-			continue;
-		ret = pps_swapoff_pmd_range(mm, vma, pud, addr, next, type);
-		if (ret == -ENOMEM)
-			return ret;
-	} while (pud++, addr = next, addr != end);
-	return 0;
-}
-
-static int pps_swapoff_pgd_range(struct mm_struct* mm, struct vm_area_struct*
-		vma, int type)
-{
-	unsigned long next;
-	unsigned long addr = vma->vm_start;
-	unsigned long end = vma->vm_end;
-	int ret;
-	pgd_t* pgd = pgd_offset(mm, addr);
-	do {
-		next = pgd_addr_end(addr, end);
-		if (pgd_none_or_clear_bad(pgd))
-			continue;
-		ret = pps_swapoff_pud_range(mm, vma, pgd, addr, next, type);
-		if (ret == -ENOMEM)
-			return ret;
-	} while (pgd++, addr = next, addr != end);
-	return 0;
-}
-
-static int pps_swapoff(int type)
-{
-	struct mm_struct* mm;
-	struct vm_area_struct* vma;
-	struct list_head *pos, *lhtemp;
-	int ret = 0;
-
-	spin_lock(&mmlist_lock);
-	list_for_each_safe(pos, lhtemp, &init_mm.mmlist) {
-		mm = list_entry(pos, struct mm_struct, mmlist);
-		if (atomic_inc_return(&mm->mm_users) == 1) {
-			atomic_dec(&mm->mm_users);
-			continue;
-		}
-		spin_unlock(&mmlist_lock);
-		down_read(&mm->mmap_sem);
-		for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
-			if (!(vma->vm_flags & VM_PURE_PRIVATE))
-				continue;
-			if (vma->vm_flags & VM_LOCKED)
-				continue;
-			ret = pps_swapoff_pgd_range(mm, vma, type);
-			if (ret == -ENOMEM)
-				break;
-		}
-		up_read(&mm->mmap_sem);
-		mmput(mm);
-		spin_lock(&mmlist_lock);
-	}
-	spin_unlock(&mmlist_lock);
-	return ret;
-}
-
@@ -780,6 +621,0 @@
-	// Let's first read all pps pages back! Note, it's one-to-one mapping.
-	retval = pps_swapoff(type);
-	if (retval == -ENOMEM) // something was wrong.
-		return -ENOMEM;
-	// Now, the remain pages are shared pages, go ahead!
-
@@ -1015 +851 @@
-	// struct list_head *p, *next;
+	struct list_head *p, *next;
@@ -1021,3 +856,0 @@
-	/*
-	 * Now, init_mm.mmlist list not only is used by SwapDevice but also is used
-	 * by PPS.
@@ -1028 +860,0 @@
-	*/
--- patch-linux/mm/memory.c	2006-12-26 15:20:02.701543280 +0800
+++ linux-2.6.16.29/mm/memory.c	2006-09-13 02:02:10.000000000 +0800
@@ -439 +439 @@
-		if (pte_swapped(pte)) {
+		if (!pte_file(pte)) {
@@ -661,2 +660,0 @@
-			// if (vma->vm_flags & VM_PURE_PRIVATE && page != ZERO_PAGE(addr))
-			// 	lru_cache_add_active(page);
@@ -682,10 +680 @@
-		if (pte_unmapped(ptent)) {
-			struct page *page;
-			page = pfn_to_page(pte_pfn(ptent));
-			pte_clear_full(mm, addr, pte, tlb->fullmm);
-			// lru_cache_add_active(page);
-			tlb_remove_page(tlb, page);
-			anon_rss--;
-			continue;
-		}
-		if (pte_swapped(ptent))
+		if (!pte_file(ptent))
@@ -1522,2 +1511 @@
-		if (!(vma->vm_flags & VM_PURE_PRIVATE))
-			lru_cache_add_active(new_page);
+		lru_cache_add_active(new_page);
@@ -1879,78 +1866,0 @@
- * New read ahead code, mainly for VM_PURE_PRIVATE only.
- */
-static void pps_swapin_readahead(swp_entry_t entry, unsigned long
addr,struct vm_area_struct *vma, pte_t* pte, pmd_t* pmd)
-{
-	struct page* page;
-	pte_t *prev, *next;
-	swp_entry_t temp;
-	spinlock_t* ptl = pte_lockptr(vma->vm_mm, pmd);
-	int swapType = swp_type(entry);
-	int swapOffset = swp_offset(entry);
-	int readahead = 1, abs;
-
-	if (!(vma->vm_flags & VM_PURE_PRIVATE)) {
-		swapin_readahead(entry, addr, vma);
-		return;
-	}
-
-	page = read_swap_cache_async(entry, vma, addr);
-	if (!page)
-		return;
-	page_cache_release(page);
-
-	// read ahead the whole series, first forward then backward.
-	while (readahead < MAX_SERIES_LENGTH) {
-		next = pte++;
-		if (next - (pte_t*) pmd >= PTRS_PER_PTE)
-			break;
-		spin_lock(ptl);
-        if (!(!pte_present(*next) && pte_swapped(*next))) {
-			spin_unlock(ptl);
-			break;
-		}
-		temp = pte_to_swp_entry(*next);
-		spin_unlock(ptl);
-		if (swp_type(temp) != swapType)
-			break;
-		abs = swp_offset(temp) - swapOffset;
-		abs = abs < 0 ? -abs : abs;
-		swapOffset = swp_offset(temp);
-		if (abs > 8)
-			// the two swap entries are too far, give up!
-			break;
-		page = read_swap_cache_async(temp, vma, addr);
-		if (!page)
-			return;
-		page_cache_release(page);
-		readahead++;
-	}
-
-	swapOffset = swp_offset(entry);
-	while (readahead < MAX_SERIES_LENGTH) {
-		prev = pte--;
-		if (prev - (pte_t*) pmd < 0)
-			break;
-		spin_lock(ptl);
-        if (!(!pte_present(*prev) && pte_swapped(*prev))) {
-			spin_unlock(ptl);
-			break;
-		}
-		temp = pte_to_swp_entry(*prev);
-		spin_unlock(ptl);
-		if (swp_type(temp) != swapType)
-			break;
-		abs = swp_offset(temp) - swapOffset;
-		abs = abs < 0 ? -abs : abs;
-		swapOffset = swp_offset(temp);
-		if (abs > 8)
-			// the two swap entries are too far, give up!
-			break;
-		page = read_swap_cache_async(temp, vma, addr);
-		if (!page)
-			return;
-		page_cache_release(page);
-		readahead++;
-	}
-}
-
-/*
@@ -1978 +1888 @@
- 		pps_swapin_readahead(entry, address, vma, page_table, pmd);
+ 		swapin_readahead(entry, address, vma);
@@ -1997,2 +1907 @@
-	if (!(vma->vm_flags & VM_PURE_PRIVATE))
-		mark_page_accessed(page);
+	mark_page_accessed(page);
@@ -2002,4 +1910,0 @@
-		if (vma->vm_flags & VM_PURE_PRIVATE) {
-			lru_cache_add_active(page);
-			mark_page_accessed(page);
-		}
@@ -2020,4 +1924,0 @@
-		if (vma->vm_flags & VM_PURE_PRIVATE) {
-			lru_cache_add_active(page);
-			mark_page_accessed(page);
-		}
@@ -2095,2 +1995,0 @@
-		if (!(vma->vm_flags & VM_PURE_PRIVATE))
-			lru_cache_add_active(page);
@@ -2097,0 +1997 @@
+		lru_cache_add_active(page);
@@ -2312,14 +2211,0 @@
-		if (pte_unmapped(entry)) {
-			BUG_ON(!(vma->vm_flags & VM_PURE_PRIVATE));
-			struct page* page = pte_page(entry);
-			pte_t temp_pte = mk_pte(page, vma->vm_page_prot);
-			pte = pte_offset_map_lock(mm, pmd, address, &ptl);
-			if (unlikely(pte_same(*pte, entry))) {
-				page_add_new_anon_rmap(page, vma, address);
-				set_pte_at(mm, address, pte, temp_pte);
-				update_mmu_cache(vma, address, temp_pte);
-				lazy_mmu_prot_update(temp_pte);
-			}
-			pte_unmap_unlock(pte, ptl);
-			return VM_FAULT_MINOR;
-		}
@@ -2562,109 +2447,0 @@
-
-static void migrate_back_pte_range(struct mm_struct* mm, pmd_t *pmd, struct
-		vm_area_struct *vma, unsigned long addr, unsigned long end)
-{
-	struct page* page;
-	pte_t entry;
-	pte_t* pte;
-	spinlock_t* ptl;
-
-	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
-	do {
-		if (!pte_present(*pte) && pte_unmapped(*pte)) {
-			page = pte_page(*pte);
-			entry = mk_pte(page, vma->vm_page_prot);
-			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
-			set_pte_at(mm, addr, pte, entry);
-			BUG_ON(page == ZERO_PAGE(addr));
-			page_add_new_anon_rmap(page, vma, addr);
-		}
-		if (pte_present(*pte)) {
-			page = pte_page(*pte);
-			if (page == ZERO_PAGE(addr))
-				continue;
-			lru_cache_add_active(page);
-		}
-	} while (pte++, addr += PAGE_SIZE, addr != end);
-	pte_unmap_unlock(pte - 1, ptl);
-	lru_add_drain();
-}
-
-static void migrate_back_pmd_range(struct mm_struct* mm, pud_t *pud, struct
-		vm_area_struct *vma, unsigned long addr, unsigned long end)
-{
-	pmd_t *pmd;
-	unsigned long next;
-
-	pmd = pmd_offset(pud, addr);
-	do {
-		next = pmd_addr_end(addr, end);
-		if (pmd_none_or_clear_bad(pmd))
-			continue;
-		migrate_back_pte_range(mm, pmd, vma, addr, next);
-	} while (pmd++, addr = next, addr != end);
-}
-
-static void migrate_back_pud_range(struct mm_struct* mm, pgd_t *pgd, struct
-		vm_area_struct *vma, unsigned long addr, unsigned long end)
-{
-	pud_t *pud;
-	unsigned long next;
-
-	pud = pud_offset(pgd, addr);
-	do {
-		next = pud_addr_end(addr, end);
-		if (pud_none_or_clear_bad(pud))
-			continue;
-		migrate_back_pmd_range(mm, pud, vma, addr, next);
-	} while (pud++, addr = next, addr != end);
-}
-
-// migrate all pages of pure private vma back to Linux legacy memory
management.
-static void migrate_back_legacy_linux(struct mm_struct* mm, struct
vm_area_struct* vma)
-{
-	pgd_t* pgd;
-	unsigned long next;
-	unsigned long addr = vma->vm_start;
-	unsigned long end = vma->vm_end;
-
-	pgd = pgd_offset(mm, addr);
-	do {
-		next = pgd_addr_end(addr, end);
-		if (pgd_none_or_clear_bad(pgd))
-			continue;
-		migrate_back_pud_range(mm, pgd, vma, addr, next);
-	} while (pgd++, addr = next, addr != end);
-}
-
-LIST_HEAD(pps_head);
-LIST_HEAD(pps_head_buddy);
-
-DEFINE_SPINLOCK(pps_lock);
-
-void enter_pps(struct mm_struct* mm, struct vm_area_struct* vma)
-{
-	int condition = VM_READ | VM_WRITE | VM_EXEC | \
-		 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC | \
-		 VM_GROWSDOWN | VM_GROWSUP | \
-		 VM_LOCKED | VM_SEQ_READ | VM_RAND_READ | VM_DONTCOPY | VM_ACCOUNT;
-	if (!(vma->vm_flags & ~condition) && vma->vm_file == NULL) {
-		vma->vm_flags |= VM_PURE_PRIVATE;
-		if (list_empty(&mm->mmlist)) {
-			spin_lock(&mmlist_lock);
-			if (list_empty(&mm->mmlist))
-				list_add(&mm->mmlist, &init_mm.mmlist);
-			spin_unlock(&mmlist_lock);
-		}
-	}
-}
-
-void leave_pps(struct vm_area_struct* vma, int migrate_flag)
-{
-	struct mm_struct* mm = vma->vm_mm;
-
-	if (vma->vm_flags & VM_PURE_PRIVATE) {
-		vma->vm_flags &= ~VM_PURE_PRIVATE;
-		if (migrate_flag)
-			migrate_back_legacy_linux(mm, vma);
-	}
-}
--- patch-linux/kernel/timer.c	2006-12-26 15:20:02.688545256 +0800
+++ linux-2.6.16.29/kernel/timer.c	2006-09-13 02:02:10.000000000 +0800
@@ -845,2 +844,0 @@
-
-	timer_flush_tlb_tasks(NULL);
--- patch-linux/kernel/fork.c	2006-12-26 15:20:02.688545256 +0800
+++ linux-2.6.16.29/kernel/fork.c	2006-09-13 02:02:10.000000000 +0800
@@ -232 +231,0 @@
-		leave_pps(mpnt, 1);
--- patch-linux/Documentation/vm_pps.txt	2006-12-26 15:45:33.203883456 +0800
+++ linux-2.6.16.29/Documentation/vm_pps.txt	1970-01-01 08:00:00.000000000 +0800
@@ -1,190 +0,0 @@
-                         Pure Private Page System (pps)
-                     Copyright by Yunfeng Zhang on GFDL 1.2
-                              zyf.zeroos@gmail.com
-                              December 24-26, 2006
-
-// Purpose <([{
-The file is used to document the idea which is published firstly at
-http://www.ussg.iu.edu/hypermail/linux/kernel/0607.2/0451.html, as a part of my
-OS -- main page http://blog.chinaunix.net/u/21764/index.php.  You can find the
-overview of the idea in section <How to Reclaim Pages more Efficiently> and how
-I patch it into Linux 2.6.16.29 in section <Pure Private Page System -- pps>.
-// }])>
-
-// How to Reclaim Pages more Efficiently <([{
-Good idea originates from overall design and management ability, when you look
-down from a manager view, you will relief yourself from disordered code and
-find some problem immediately.
-
-OK! to modern OS, its memory subsystem can be divided into three layers
-1) Space layer (InodeSpace, UserSpace and CoreSpace).
-2) VMA layer (PrivateVMA and SharedVMA, memory architecture-independent layer).
-3) PTE and page layer (architecture-dependent).
-
-Since the 2nd layer assembles the much statistic of page-acess information, so
-it's nature that swap subsystem should be deployed and implemented on the 2nd
-layer.
-
-Undoubtedly, there are some virtues about it
-1) SwapDaemon can collect the statistic of process acessing pages and by it
-   unmaps ptes, SMP specially benefits from it for we can use flush_tlb_range
-   to relief frequently TLB IPI interrupt.
-2) Page-fault can issue better readahead requests since history data shows all
-   related pages have conglomerating affinity.
-3) It's conformable to POSIX madvise API family.
-
-Unfortunately, Linux 2.6.16.29 swap subsystem is based on the 3rd layer -- a
-system surrounding page.
-
-I've commited a patch to it, see section <Pure Private Page System --
pps>. Note, it ISN'T perfect.
-// }])>
-
-// Pure Private Page System -- pps  <([{
-Current Linux is just like a monster and still growing, even its swap subsystem
-...
-
-As I've referred in previous section, perfectly applying my idea need to unroot
-page-surrounging swap subsystem to migrate it on VMA, but a huge gap has
-defeated me -- active_list and inactive_list. In fact, you can find
-lru_add_active anywhere ... It's IMPOSSIBLE to me to complete it only by
-myself. It's also the difference between my design and Linux, in my OS, page is
-the charge of its new owner totally, however, to Linux, page management system
-is still tracing it by PG_active flag.
-
-So I conceive another solution:) That is, set up an independent page-recycle
-system rooted on Linux legacy page system -- pps, intercept all private pages
-belonging to PrivateVMA to pps, then use my pps to cycle them.  By the way, the
-whole job should be consist of two parts, here is the first --
-PrivateVMA-oriented (PPS), other is SharedVMA-oriented (should be called SPS)
-scheduled in future. Of course, if all are done, it will empty Linux legacy
-page system.
-
-In fact, pps is centered on how to better collect and unmap process private
-pages in SwapDaemon mm/vmscan.c:shrink_private_vma, the whole process is
-divided into six stages -- <Stage Definition>. Other sections show the remain
-aspects of pps
-1) <Data Definition> is basic data definition.
-2) <Concurrent racers of Shrinking pps> is focused on synchronization.
-3) <Private Page Lifecycle of pps> -- how private pages enter in/go off pps.
-4) <VMA Lifecycle of pps> which VMA is belonging to pps.
-
-PPS uses init_mm.mm_list list to enumerate all swappable UserSpace.
-
-I'm also glad to highlight my a new idea -- dftlb which is described in
-section <Delay to Flush TLB>.
-// }])>
-
-// Delay to Flush TLB (dftlb) <([{
-Delay to flush TLB is instroduced by me to enhance flushing TLB efficiency, in
-brief, when we want to unmap a page from the page table of a process, why we
-send TLB IPI to other CPUs immediately, since every CPU has timer interrupt, we
-can insert flushing tasks into timer interrupt route to implement a
-free-charged TLB flushing.
-
-The trick is implemented in
-1) TLB flushing task is added in fill_in_tlb_task of mm/vmscan.c.
-2) timer_flush_tlb_tasks of kernel/timer.c is used by other CPUs to execute
-   flushing tasks.
-3) all data are defined in include/linux/mm.h.
-
-The restriction of dftlb. Following conditions must be met
-1) atomic cmpxchg instruction.
-2) atomically set the access bit after they touch a pte firstly.
-3) To some architectures, vma parameter of flush_tlb_range is maybe important,
-   if it's true, since it's possible that the vma of a TLB flushing task has
-   gone when a CPU starts to execute the task in timer interrupt, so don't use
-   dftlb.
-combine stage 1 with stage 2, and send IPI immediately in fill_in_tlb_tasks.
-// }])>
-
-// Stage Definition <([{
-The whole process of private page page-out is divided into six stages, as
-showed in shrink_pvma_scan_ptes of mm/vmscan.c
-1) PTE to untouched PTE (access bit is cleared), append flushing
tasks to dftlb.
-2) Convert untouched PTE to UnmappedPTE.
-3) Link SwapEntry to every UnmappedPTE.
-4) Synchronize the page of a UnmappedPTE with its physical swap page.
-5) Reclaimed the page and shift UnmappedPTE to SwappedPTE.
-6) SwappedPTE stage.
-// }])>
-
-// Data Definition <([{
-New VMA flag (VM_PURE_PRIVATE) is appended into VMA in include/linux/mm.h.
-
-New PTE type (UnmappedPTE) is appended into PTE system in
-include/asm-i386/pgtable.h.
-// }])>
-
-// Concurrent Racers of Shrinking pps <([{
-shrink_private_vma of mm/vmscan.c uses init_mm.mmlist to scan all swappable
-mm_struct instances, during the process of scaning and reclaiming process, it
-readlockes every mm_struct object, which brings some potential concurrent
-racers
-1) mm/swapfile.c    pps_swapoff (swapoff API).
-2) mm/memory.c  do_wp_page, handle_pte_fault::unmapped_pte, do_anonymous_page
-   (page-fault).
-// }])>
-
-// Private Page Lifecycle of pps <([{
-All pages belonging to pps are called as pure private page.
-
-IN (NOTE, when a pure private page enters into pps, it's also trimmed from
-Linux legacy page system by commeting lru_cache_add_active clause)
-1) fs/exec.c	install_arg_pages	(argument pages).
-2) mm/memory	do_anonymous_page, do_wp_page, do_swap_page	(page fault).
-3) mm/swap_state.c	read_swap_cache_async	(swap pages).
-
-OUT
-1) mm/vmscan.c  shrink_pvma_scan_ptes   (stage 6, reclaim a private page).
-2) mm/memory    zap_pte_range   (free a page).
-3) kernel/fork.c	dup_mmap	(if someone uses fork, migrate all pps pages
-   back to let Linux legacy page system manage them).
-
-When a pure private page is in pps, it can be visited simultaneously by
-page-fault and SwapDaemon.
-// }])>
-
-// VMA Lifecycle of pps <([{
-When a PrivateVMA enters into pps, it's or-ed a new flag -- VM_PURE_PRIVATE,
-the flag is used in the shrink_private_vma of mm/vmscan.c.  Other fields are
-reserved untouch state.
-
-IN.
-1) fs/exec.c	setup_arg_pages	(StackVMA).
-2) mm/mmap.c	do_mmap_pgoff, do_brk	(DataVMA).
-3) mm/mmap.c	split_vma, copy_vma	(in some cases, we need copy a VMA from an
-   exist VMA).
-
-OUT.
-1) kernel/fork.c	dup_mmap	(if someone uses fork, return the vma back to
-   Linux legacy system).
-2) mm/mmap.c	remove_vma, vma_adjust	(destroy VMA).
-3) mm/mmap.c	do_mmap_pgoff	(delete VMA when some errors occur).
-// }])>
-
-// Postscript <([{
-Note, some circumstances aren't tested due to hardware restriction e.g. SMP
-dftlb.
-
-Here are some improvements about pps
-1) In fact, I recommend one-to-one private model -- PrivateVMA, (PTE,
-   UnmappedPTE) and PrivatePage which is described in my OS and the aboved
-   hyperlink of Linux kernel mail list. So it's a compromise to use Linux
-   legacy SwapCache in my pps.
-2) SwapCache should provide more flexible interfaces, shrink_pvma_scan_ptes
-   need allocate swap entries in batch, exactly, allocate a batch of fake
-   continual swap entries, see mm/pps_swapin_readahead.
-3) pps statistic entry in /proc/meminfo.
-4) a better arithmetic to pick mm out to scan and shrink in shrink_private_vma.
-5) It's better to execute the first 2 stages when system is idle, current
-   SwapDaemon only is activated when free pages are low.
-6) A scanning count should be added into mm_struct, so when the count is
-   becoming enough old to open stage 3 and 4.
-
-I'm still working on improvement 4, 5 and 6 to find out how to maximum the
-performance of swap subsystem.
-
-If Linux kernel group can't make a schedule to re-write their memory code,
-however, pps maybe is the best solution until now.
-// }])>
-// vim: foldmarker=<([{,}])> foldmethod=marker et
--- patch-linux/include/linux/mm.h	2006-12-26 15:20:02.685545712 +0800
+++ linux-2.6.16.29/include/linux/mm.h	2006-09-13 02:02:10.000000000 +0800
@@ -169,2 +168,0 @@
-#define VM_PURE_PRIVATE	0x04000000	/* Is the vma is only belonging to a mm,
-									   see more from Documentation/vm_pps.txt */
@@ -1061,18 +1058,0 @@
-/* vmscan.c::delay flush TLB */
-struct delay_tlb_task_t
-{
-	struct mm_struct* mm; //__attribute__ ((section(".pure_private_vma.data")));
-	cpumask_t cpu_mask;
-	struct vm_area_struct* vma[32];
-	unsigned long start[32];
-	unsigned long end[32];
-};
-extern struct delay_tlb_task_t delay_tlb_tasks[32];
-
-// The prototype of the function is fit with the "func" of "int
smp_call_function (void (*func) (void *info), void *info, int retry,
int wait);" of include/linux/smp.h of 2.6.16.29. Call it with NULL.
-void timer_flush_tlb_tasks(void* data /* = NULL */);
-
-void enter_pps(struct mm_struct* mm, struct vm_area_struct* vma);
-void leave_pps(struct vm_area_struct* vma, int migrate_flag);
-
-#define MAX_SERIES_LENGTH 8
--- patch-linux/include/linux/swapops.h	2006-12-26 15:20:02.686545560 +0800
+++ linux-2.6.16.29/include/linux/swapops.h	2006-09-13 02:02:10.000000000 +0800
@@ -53 +53 @@
-	BUG_ON(!pte_swapped(pte));
+	BUG_ON(pte_file(pte));
@@ -67 +67 @@
-	BUG_ON(!pte_swapped(__swp_entry_to_pte(arch_entry)));
+	BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));
--- patch-linux/include/asm-i386/pgtable-2level.h	2006-12-26
15:20:02.687545408 +0800
+++ linux-2.6.16.29/include/asm-i386/pgtable-2level.h	2006-09-13
02:02:10.000000000 +0800
@@ -49 +49 @@
- * Bits 0, 5, 6 and 7 are taken, split up the 28 bits of offset
+ * Bits 0, 6 and 7 are taken, split up the 29 bits of offset
@@ -52 +52 @@
-#define PTE_FILE_MAX_BITS	28
+#define PTE_FILE_MAX_BITS	29
@@ -55 +55 @@
-	((((pte).pte_low >> 1) & 0xf ) + (((pte).pte_low >> 8) << 4 ))
+	((((pte).pte_low >> 1) & 0x1f ) + (((pte).pte_low >> 8) << 5 ))
@@ -58 +58 @@
-	((pte_t) { (((off) & 0xf) << 1) + (((off) >> 4) << 8) + _PAGE_FILE })
+	((pte_t) { (((off) & 0x1f) << 1) + (((off) >> 5) << 8) + _PAGE_FILE })
@@ -61 +61 @@
-#define __swp_type(x)			(((x).val >> 1) & 0xf)
+#define __swp_type(x)			(((x).val >> 1) & 0x1f)
@@ -63 +63 @@
-#define __swp_entry(type, offset)	((swp_entry_t) { ((type & 0xf) <<
1) | ((offset) << 8) | _PAGE_SWAPPED })
+#define __swp_entry(type, offset)	((swp_entry_t) { ((type) << 1) |
((offset) << 8) })
--- patch-linux/include/asm-i386/pgtable.h	2006-12-26 15:20:02.687545408 +0800
+++ linux-2.6.16.29/include/asm-i386/pgtable.h	2006-09-13
02:02:10.000000000 +0800
@@ -124,5 +124 @@
-#define _PAGE_UNMAPPED	0x020	/* a special PTE type, hold its page reference
-								   even it's unmapped, see more from
-								   Documentation/vm_pps.txt. */
-#define _PAGE_SWAPPED 0x040 /* swapped PTE. */
-#define _PAGE_FILE	0x060	/* nonlinear file mapping, saved PTE; */
+#define _PAGE_FILE	0x040	/* nonlinear file mapping, saved PTE; unset:swap */
@@ -235,3 +231 @@
-static inline int pte_unmapped(pte_t pte)	{ return ((pte).pte_low &
0x60) == _PAGE_UNMAPPED; }
-static inline int pte_swapped(pte_t pte)	{ return ((pte).pte_low &
0x60) == _PAGE_SWAPPED; }
-static inline int pte_file(pte_t pte)		{ return ((pte).pte_low &
0x60) == _PAGE_FILE; }
+static inline int pte_file(pte_t pte)		{ return (pte).pte_low & _PAGE_FILE; }

             reply	other threads:[~2006-12-26  8:18 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-12-26  8:18 yunfeng zhang [this message]
2006-12-26  9:03 ` Zhou Yingchao
2006-12-27  3:33   ` yunfeng zhang
2006-12-30  5:50     ` Zhou Yingchao
2007-01-05  7:35       ` yunfeng zhang
2007-01-05  7:45         ` yunfeng zhang
2006-12-27  3:38 ` yunfeng zhang
2006-12-27 18:44 ` Pavel Machek
2006-12-29  6:45   ` yunfeng zhang
2006-12-29  9:15     ` Pavel Machek
2006-12-29 15:50       ` Randy Dunlap
2007-01-05 23:10 zyf.zeroos
2007-01-09  8:27 ` yunfeng zhang
     [not found] <200701092047.43248.a1426z@gawab.com>
2007-01-10  2:51 ` yunfeng zhang

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