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* [PATCH net-next-2.6 0/5] RFS hardware acceleration (v3)
@ 2011-01-19 20:59 Ben Hutchings
  2011-01-19 21:02 ` [PATCH net-next-2.6 1/5] genirq: Add IRQ affinity notifiers Ben Hutchings
  2011-01-19 21:03 ` [PATCH net-next-2.6 2/5] lib: cpu_rmap: CPU affinity reverse-mapping Ben Hutchings
  0 siblings, 2 replies; 5+ messages in thread
From: Ben Hutchings @ 2011-01-19 20:59 UTC (permalink / raw)
  To: David Miller, Thomas Gleixner, Tom Herbert
  Cc: netdev, linux-net-drivers, linux-kernel

This patch series extends RFS to use hardware RX filters where
available.  Depending on the number of hardware RX queues and their
IRQs' affinity, this should reduce the need for IPIs or at least get
packets delivered to the right NUMA node.

The first patch implements IRQ affinity notifiers, based on the outline
that Thomas Gleixner wrote in response to the previous version of this
patch series.  This has been updated based on Thomas's previous comments.

The second patch is a generalisation of the CPU affinity reverse-
mapping, plus functions to maintain such a mapping based on the new IRQ
affinity notifiers.  This has been updated based on Eric Dumazet's
comments.

The remaining patches add the RFS acceleration hooks and an
implementation in the sfc driver.  I have changed the sfc driver's
strategy for reclaiming entries in the filter table entry from the
previous version.  The table can now be scanned at the end of each NAPI
polling interval, based on the rate at which filters are being added.
However, I haven't yet constructed a good test case that involves
turnover of flows so I have yet to settle on a good strategy for this.

Ben.

Ben Hutchings (5):
  genirq: Add IRQ affinity notifiers
  lib: cpu_rmap: CPU affinity reverse-mapping
  net: RPS: Enable hardware acceleration of RFS
  sfc: Limit filter search depth further for performance hints (i.e.
    RFS)
  sfc: Implement hardware acceleration of RFS

 drivers/net/sfc/efx.c        |   49 ++++++++-
 drivers/net/sfc/efx.h        |   16 +++
 drivers/net/sfc/filter.c     |  107 ++++++++++++++++-
 drivers/net/sfc/net_driver.h |    3 +
 include/linux/cpu_rmap.h     |   73 ++++++++++++
 include/linux/interrupt.h    |   31 +++++
 include/linux/irqdesc.h      |    3 +
 include/linux/netdevice.h    |   33 +++++-
 kernel/irq/manage.c          |   82 +++++++++++++
 lib/Kconfig                  |    4 +
 lib/Makefile                 |    2 +
 lib/cpu_rmap.c               |  269 ++++++++++++++++++++++++++++++++++++++++++
 net/Kconfig                  |    6 +
 net/core/dev.c               |   97 ++++++++++++++-
 14 files changed, 760 insertions(+), 15 deletions(-)
 create mode 100644 include/linux/cpu_rmap.h
 create mode 100644 lib/cpu_rmap.c

-- 
1.7.3.4


-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH net-next-2.6 1/5] genirq: Add IRQ affinity notifiers
  2011-01-19 20:59 [PATCH net-next-2.6 0/5] RFS hardware acceleration (v3) Ben Hutchings
@ 2011-01-19 21:02 ` Ben Hutchings
  2011-01-22 16:37   ` [tip:irq/numa] " tip-bot for Ben Hutchings
  2011-01-19 21:03 ` [PATCH net-next-2.6 2/5] lib: cpu_rmap: CPU affinity reverse-mapping Ben Hutchings
  1 sibling, 1 reply; 5+ messages in thread
From: Ben Hutchings @ 2011-01-19 21:02 UTC (permalink / raw)
  To: Thomas Gleixner; +Cc: netdev, linux-net-drivers, Tom Herbert, David Miller

When initiating I/O on a multiqueue and multi-IRQ device, we may want
to select a queue for which the response will be handled on the same
or a nearby CPU.  This requires a reverse-map of IRQ affinity.  Add a
notification mechanism to support this.

This is based closely on work by Thomas Gleixner <tglx@linutronix.de>.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
---
Thomas, I hope this answers all your comments.  If you are happy with
this, can it go into net-next-2.6 so the rest of this series can get
into 2.6.39?

Ben.

 include/linux/interrupt.h |   31 +++++++++++++++++
 include/linux/irqdesc.h   |    3 ++
 kernel/irq/manage.c       |   82 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 116 insertions(+), 0 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 55e0d42..9823e37 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -14,6 +14,8 @@
 #include <linux/smp.h>
 #include <linux/percpu.h>
 #include <linux/hrtimer.h>
+#include <linux/kref.h>
+#include <linux/workqueue.h>
 
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
@@ -240,6 +242,35 @@ extern int irq_can_set_affinity(unsigned int irq);
 extern int irq_select_affinity(unsigned int irq);
 
 extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m);
+
+/**
+ * struct irq_affinity_notify - context for notification of IRQ affinity changes
+ * @irq:		Interrupt to which notification applies
+ * @kref:		Reference count, for internal use
+ * @work:		Work item, for internal use
+ * @notify:		Function to be called on change.  This will be
+ *			called in process context.
+ * @release:		Function to be called on release.  This will be
+ *			called in process context.  Once registered, the
+ *			structure must only be freed when this function is
+ *			called or later.
+ */
+struct irq_affinity_notify {
+        unsigned int irq;
+        struct kref kref;
+        struct work_struct work;
+        void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
+        void (*release)(struct kref *ref);
+};
+
+extern int
+irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify);
+
+static inline void irq_run_affinity_notifiers(void)
+{
+	flush_scheduled_work();
+}
+
 #else /* CONFIG_SMP */
 
 static inline int irq_set_affinity(unsigned int irq, const struct cpumask *m)
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 6a64c6f..b98ffa4 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -8,6 +8,7 @@
  * For now it's included from <linux/irq.h>
  */
 
+struct irq_affinity_notify;
 struct proc_dir_entry;
 struct timer_rand_state;
 /**
@@ -24,6 +25,7 @@ struct timer_rand_state;
  * @last_unhandled:	aging timer for unhandled count
  * @irqs_unhandled:	stats field for spurious unhandled interrupts
  * @lock:		locking for SMP
+ * @affinity_notify:	context for notification of affinity changes
  * @pending_mask:	pending rebalanced interrupts
  * @threads_active:	number of irqaction threads currently running
  * @wait_for_threads:	wait queue for sync_irq to wait for threaded handlers
@@ -70,6 +72,7 @@ struct irq_desc {
 	raw_spinlock_t		lock;
 #ifdef CONFIG_SMP
 	const struct cpumask	*affinity_hint;
+	struct irq_affinity_notify *affinity_notify;
 #ifdef CONFIG_GENERIC_PENDING_IRQ
 	cpumask_var_t		pending_mask;
 #endif
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0caa59f..e48019e 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -134,6 +134,10 @@ int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
 		irq_set_thread_affinity(desc);
 	}
 #endif
+	if (desc->affinity_notify) {
+		kref_get(&desc->affinity_notify->kref);
+		schedule_work(&desc->affinity_notify->work);
+	}
 	desc->status |= IRQ_AFFINITY_SET;
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 	return 0;
@@ -155,6 +159,79 @@ int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 }
 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 
+static void irq_affinity_notify(struct work_struct *work)
+{
+	struct irq_affinity_notify *notify =
+		container_of(work, struct irq_affinity_notify, work);
+	struct irq_desc *desc = irq_to_desc(notify->irq);
+	cpumask_var_t cpumask;
+	unsigned long flags;
+
+	if (!desc)
+		goto out;
+
+	if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))
+		goto out;
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+#ifdef CONFIG_GENERIC_PENDING_IRQ
+	if (desc->status & IRQ_MOVE_PENDING)
+		cpumask_copy(cpumask, desc->pending_mask);
+	else
+#endif
+		cpumask_copy(cpumask, desc->affinity);
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+	notify->notify(notify, cpumask);
+
+	free_cpumask_var(cpumask);
+out:
+	kref_put(&notify->kref, notify->release);
+}
+
+/**
+ *	irq_set_affinity_notifier - control notification of IRQ affinity changes
+ *	@irq:		Interrupt for which to enable/disable notification
+ *	@notify:	Context for notification, or %NULL to disable
+ *			notification.  Function pointers must be initialised;
+ *			the other fields will be initialised by this function.
+ *
+ *	Must be called in process context.  Notification may only be enabled
+ *	after the IRQ is allocated and must be disabled before the IRQ is
+ *	freed using free_irq().
+ */
+int
+irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	struct irq_affinity_notify *old_notify;
+	unsigned long flags;
+
+	/* The release function is promised process context */
+	might_sleep();
+
+	if (!desc)
+		return -EINVAL;
+
+	/* Complete initialisation of *notify */
+	if (notify) {
+		notify->irq = irq;
+		kref_init(&notify->kref);
+		INIT_WORK(&notify->work, irq_affinity_notify);
+	}
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	old_notify = desc->affinity_notify;
+	desc->affinity_notify = notify;
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+	if (old_notify)
+		kref_put(&old_notify->kref, old_notify->release);
+	
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
+
 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 /*
  * Generic version of the affinity autoselector.
@@ -1004,6 +1081,11 @@ void free_irq(unsigned int irq, void *dev_id)
 	if (!desc)
 		return;
 
+#ifdef CONFIG_SMP
+	if (WARN_ON(desc->affinity_notify))
+		desc->affinity_notify = NULL;
+#endif
+
 	chip_bus_lock(desc);
 	kfree(__free_irq(irq, dev_id));
 	chip_bus_sync_unlock(desc);
-- 
1.7.3.4



-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH net-next-2.6 2/5] lib: cpu_rmap: CPU affinity reverse-mapping
  2011-01-19 20:59 [PATCH net-next-2.6 0/5] RFS hardware acceleration (v3) Ben Hutchings
  2011-01-19 21:02 ` [PATCH net-next-2.6 1/5] genirq: Add IRQ affinity notifiers Ben Hutchings
@ 2011-01-19 21:03 ` Ben Hutchings
  2011-01-24 23:01   ` David Miller
  1 sibling, 1 reply; 5+ messages in thread
From: Ben Hutchings @ 2011-01-19 21:03 UTC (permalink / raw)
  To: David Miller, Thomas Gleixner
  Cc: netdev, linux-net-drivers, Tom Herbert, linux-kernel

When initiating I/O on a multiqueue and multi-IRQ device, we may want
to select a queue for which the response will be handled on the same
or a nearby CPU.  This requires a reverse-map of IRQ affinity.  Add
library functions to support a generic reverse-mapping from CPUs to
objects with affinity and the specific case where the objects are
IRQs.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
---
 include/linux/cpu_rmap.h |   73 +++++++++++++
 lib/Kconfig              |    4 +
 lib/Makefile             |    2 +
 lib/cpu_rmap.c           |  269 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 348 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/cpu_rmap.h
 create mode 100644 lib/cpu_rmap.c

diff --git a/include/linux/cpu_rmap.h b/include/linux/cpu_rmap.h
new file mode 100644
index 0000000..473771a
--- /dev/null
+++ b/include/linux/cpu_rmap.h
@@ -0,0 +1,73 @@
+/*
+ * cpu_rmap.c: CPU affinity reverse-map support
+ * Copyright 2011 Solarflare Communications Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation, incorporated herein by reference.
+ */
+
+#include <linux/cpumask.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+
+/**
+ * struct cpu_rmap - CPU affinity reverse-map
+ * @size: Number of objects to be reverse-mapped
+ * @used: Number of objects added
+ * @obj: Pointer to array of object pointers
+ * @near: For each CPU, the index and distance to the nearest object,
+ *      based on affinity masks
+ */
+struct cpu_rmap {
+	u16		size, used;
+	void		**obj;
+	struct {
+		u16	index;
+		u16	dist;
+	}		near[0];
+};
+#define CPU_RMAP_DIST_INF 0xffff
+
+extern struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags);
+
+/**
+ * free_cpu_rmap - free CPU affinity reverse-map
+ * @rmap: Reverse-map allocated with alloc_cpu_rmap(), or %NULL
+ */
+static inline void free_cpu_rmap(struct cpu_rmap *rmap)
+{
+	kfree(rmap);
+}
+
+extern int cpu_rmap_add(struct cpu_rmap *rmap, void *obj);
+extern int cpu_rmap_update(struct cpu_rmap *rmap, u16 index,
+			   const struct cpumask *affinity);
+
+static inline u16 cpu_rmap_lookup_index(struct cpu_rmap *rmap, unsigned int cpu)
+{
+	return rmap->near[cpu].index;
+}
+
+static inline void *cpu_rmap_lookup_obj(struct cpu_rmap *rmap, unsigned int cpu)
+{
+	return rmap->obj[rmap->near[cpu].index];
+}
+
+#ifdef CONFIG_GENERIC_HARDIRQS
+
+/**
+ * alloc_irq_cpu_rmap - allocate CPU affinity reverse-map for IRQs
+ * @size: Number of objects to be mapped
+ *
+ * Must be called in process context.
+ */
+static inline struct cpu_rmap *alloc_irq_cpu_rmap(unsigned int size)
+{
+	return alloc_cpu_rmap(size, GFP_KERNEL);
+}
+extern void free_irq_cpu_rmap(struct cpu_rmap *rmap);
+
+extern int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq);
+
+#endif
diff --git a/lib/Kconfig b/lib/Kconfig
index 0ee67e0..8334342 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -201,6 +201,10 @@ config DISABLE_OBSOLETE_CPUMASK_FUNCTIONS
        bool "Disable obsolete cpumask functions" if DEBUG_PER_CPU_MAPS
        depends on EXPERIMENTAL && BROKEN
 
+config CPU_RMAP
+	bool
+	depends on SMP
+
 #
 # Netlink attribute parsing support is select'ed if needed
 #
diff --git a/lib/Makefile b/lib/Makefile
index cbb774f..b73ba01 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -110,6 +110,8 @@ obj-$(CONFIG_ATOMIC64_SELFTEST) += atomic64_test.o
 
 obj-$(CONFIG_AVERAGE) += average.o
 
+obj-$(CONFIG_CPU_RMAP) += cpu_rmap.o
+
 hostprogs-y	:= gen_crc32table
 clean-files	:= crc32table.h
 
diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c
new file mode 100644
index 0000000..987acfa
--- /dev/null
+++ b/lib/cpu_rmap.c
@@ -0,0 +1,269 @@
+/*
+ * cpu_rmap.c: CPU affinity reverse-map support
+ * Copyright 2011 Solarflare Communications Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation, incorporated herein by reference.
+ */
+
+#include <linux/cpu_rmap.h>
+#ifdef CONFIG_GENERIC_HARDIRQS
+#include <linux/interrupt.h>
+#endif
+#include <linux/module.h>
+
+/*
+ * These functions maintain a mapping from CPUs to some ordered set of
+ * objects with CPU affinities.  This can be seen as a reverse-map of
+ * CPU affinity.  However, we do not assume that the object affinities
+ * cover all CPUs in the system.  For those CPUs not directly covered
+ * by object affinities, we attempt to find a nearest object based on
+ * CPU topology.
+ */
+
+/**
+ * alloc_cpu_rmap - allocate CPU affinity reverse-map
+ * @size: Number of objects to be mapped
+ * @flags: Allocation flags e.g. %GFP_KERNEL
+ */
+struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags)
+{
+	struct cpu_rmap *rmap;
+	unsigned int cpu;
+	size_t obj_offset;
+
+	/* This is a silly number of objects, and we use u16 indices. */
+	if (size > 0xffff)
+		return NULL;
+
+	/* Offset of object pointer array from base structure */
+	obj_offset = ALIGN(offsetof(struct cpu_rmap, near[nr_cpu_ids]),
+			   sizeof(void *));
+
+	rmap = kzalloc(obj_offset + size * sizeof(rmap->obj[0]), flags);
+	if (!rmap)
+		return NULL;
+
+	rmap->obj = (void **)((char *)rmap + obj_offset);
+
+	/* Initially assign CPUs to objects on a rota, since we have
+	 * no idea where the objects are.  Use infinite distance, so
+	 * any object with known distance is preferable.  Include the
+	 * CPUs that are not present/online, since we definitely want
+	 * any newly-hotplugged CPUs to have some object assigned.
+	 */
+	for_each_possible_cpu(cpu) {
+		rmap->near[cpu].index = cpu % size;
+		rmap->near[cpu].dist = CPU_RMAP_DIST_INF;
+	}
+
+	rmap->size = size;
+	return rmap;
+}
+EXPORT_SYMBOL(alloc_cpu_rmap);
+
+/* Reevaluate nearest object for given CPU, comparing with the given
+ * neighbours at the given distance.
+ */
+static bool cpu_rmap_copy_neigh(struct cpu_rmap *rmap, unsigned int cpu,
+				const struct cpumask *mask, u16 dist)
+{
+	int neigh;
+
+	for_each_cpu(neigh, mask) {
+		if (rmap->near[cpu].dist > dist &&
+		    rmap->near[neigh].dist <= dist) {
+			rmap->near[cpu].index = rmap->near[neigh].index;
+			rmap->near[cpu].dist = dist;
+			return true;
+		}
+	}
+	return false;
+}
+
+#ifdef DEBUG
+static void debug_print_rmap(const struct cpu_rmap *rmap, const char *prefix)
+{
+	unsigned index;
+	unsigned int cpu;
+
+	pr_info("cpu_rmap %p, %s:\n", rmap, prefix);
+
+	for_each_possible_cpu(cpu) {
+		index = rmap->near[cpu].index;
+		pr_info("cpu %d -> obj %u (distance %u)\n",
+			cpu, index, rmap->near[cpu].dist);
+	}
+}
+#else
+static inline void
+debug_print_rmap(const struct cpu_rmap *rmap, const char *prefix)
+{
+}
+#endif
+
+/**
+ * cpu_rmap_add - add object to a rmap
+ * @rmap: CPU rmap allocated with alloc_cpu_rmap()
+ * @obj: Object to add to rmap
+ *
+ * Return index of object.
+ */
+int cpu_rmap_add(struct cpu_rmap *rmap, void *obj)
+{
+	u16 index;
+
+	BUG_ON(rmap->used >= rmap->size);
+	index = rmap->used++;
+	rmap->obj[index] = obj;
+	return index;
+}
+EXPORT_SYMBOL(cpu_rmap_add);
+
+/**
+ * cpu_rmap_update - update CPU rmap following a change of object affinity
+ * @rmap: CPU rmap to update
+ * @index: Index of object whose affinity changed
+ * @affinity: New CPU affinity of object
+ */
+int cpu_rmap_update(struct cpu_rmap *rmap, u16 index,
+		    const struct cpumask *affinity)
+{
+	cpumask_var_t update_mask;
+	unsigned int cpu;
+
+	if (unlikely(!zalloc_cpumask_var(&update_mask, GFP_KERNEL)))
+		return -ENOMEM;
+
+	/* Invalidate distance for all CPUs for which this used to be
+	 * the nearest object.  Mark those CPUs for update.
+	 */
+	for_each_online_cpu(cpu) {
+		if (rmap->near[cpu].index == index) {
+			rmap->near[cpu].dist = CPU_RMAP_DIST_INF;
+			cpumask_set_cpu(cpu, update_mask);
+		}
+	}
+
+	debug_print_rmap(rmap, "after invalidating old distances");
+
+	/* Set distance to 0 for all CPUs in the new affinity mask.
+	 * Mark all CPUs within their NUMA nodes for update.
+	 */
+	for_each_cpu(cpu, affinity) {
+		rmap->near[cpu].index = index;
+		rmap->near[cpu].dist = 0;
+		cpumask_or(update_mask, update_mask,
+			   cpumask_of_node(cpu_to_node(cpu)));
+	}
+
+	debug_print_rmap(rmap, "after updating neighbours");
+
+	/* Update distances based on topology */
+	for_each_cpu(cpu, update_mask) {
+		if (cpu_rmap_copy_neigh(rmap, cpu,
+					topology_thread_cpumask(cpu), 1))
+			continue;
+		if (cpu_rmap_copy_neigh(rmap, cpu,
+					topology_core_cpumask(cpu), 2))
+			continue;
+		if (cpu_rmap_copy_neigh(rmap, cpu,
+					cpumask_of_node(cpu_to_node(cpu)), 3))
+			continue;
+		/* We could continue into NUMA node distances, but for now
+		 * we give up.
+		 */
+	}
+
+	debug_print_rmap(rmap, "after copying neighbours");
+
+	free_cpumask_var(update_mask);
+	return 0;
+}
+EXPORT_SYMBOL(cpu_rmap_update);
+
+#ifdef CONFIG_GENERIC_HARDIRQS
+
+/* Glue between IRQ affinity notifiers and CPU rmaps */
+
+struct irq_glue {
+	struct irq_affinity_notify notify;
+	struct cpu_rmap *rmap;
+	u16 index;
+};
+
+/**
+ * free_irq_cpu_rmap - free a CPU affinity reverse-map used for IRQs
+ * @rmap: Reverse-map allocated with alloc_irq_cpu_map(), or %NULL
+ *
+ * Must be called in process context, before freeing the IRQs, and
+ * without holding any locks required by global workqueue items.
+ */
+void free_irq_cpu_rmap(struct cpu_rmap *rmap)
+{
+	struct irq_glue *glue;
+	u16 index;
+
+	if (!rmap)
+		return;
+
+	for (index = 0; index < rmap->used; index++) {
+		glue = rmap->obj[index];
+		irq_set_affinity_notifier(glue->notify.irq, NULL);
+	}
+	irq_run_affinity_notifiers();
+
+	kfree(rmap);
+}
+EXPORT_SYMBOL(free_irq_cpu_rmap);
+
+static void
+irq_cpu_rmap_notify(struct irq_affinity_notify *notify, const cpumask_t *mask)
+{
+	struct irq_glue *glue =
+		container_of(notify, struct irq_glue, notify);
+	int rc;
+
+	rc = cpu_rmap_update(glue->rmap, glue->index, mask);
+	if (rc)
+		pr_warning("irq_cpu_rmap_notify: update failed: %d\n", rc);
+}
+
+static void irq_cpu_rmap_release(struct kref *ref)
+{
+	struct irq_glue *glue =
+		container_of(ref, struct irq_glue, notify.kref);
+	kfree(glue);
+}
+
+/**
+ * irq_cpu_rmap_add - add an IRQ to a CPU affinity reverse-map
+ * @rmap: The reverse-map
+ * @irq: The IRQ number
+ *
+ * This adds an IRQ affinity notifier that will update the reverse-map
+ * automatically.
+ *
+ * Must be called in process context, after the IRQ is allocated but
+ * before it is bound with request_irq().
+ */
+int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq)
+{
+	struct irq_glue *glue = kzalloc(sizeof(*glue), GFP_KERNEL);
+	int rc;
+
+	if (!glue)
+		return -ENOMEM;
+	glue->notify.notify = irq_cpu_rmap_notify;
+	glue->notify.release = irq_cpu_rmap_release;
+	glue->rmap = rmap;
+	glue->index = cpu_rmap_add(rmap, glue);
+	rc = irq_set_affinity_notifier(irq, &glue->notify);
+	if (rc)
+		kfree(glue);
+	return rc;
+}
+EXPORT_SYMBOL(irq_cpu_rmap_add);
+
+#endif /* CONFIG_GENERIC_HARDIRQS */
-- 
1.7.3.4



-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [tip:irq/numa] genirq: Add IRQ affinity notifiers
  2011-01-19 21:02 ` [PATCH net-next-2.6 1/5] genirq: Add IRQ affinity notifiers Ben Hutchings
@ 2011-01-22 16:37   ` tip-bot for Ben Hutchings
  0 siblings, 0 replies; 5+ messages in thread
From: tip-bot for Ben Hutchings @ 2011-01-22 16:37 UTC (permalink / raw)
  To: linux-tip-commits
  Cc: linux-kernel, hpa, mingo, tglx, therbert, bhutchings, davem

Commit-ID:  cd7eab44e9946c28d595abe3e9a43e945bc49141
Gitweb:     http://git.kernel.org/tip/cd7eab44e9946c28d595abe3e9a43e945bc49141
Author:     Ben Hutchings <bhutchings@solarflare.com>
AuthorDate: Wed, 19 Jan 2011 21:01:44 +0000
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 22 Jan 2011 17:34:25 +0100

genirq: Add IRQ affinity notifiers

When initiating I/O on a multiqueue and multi-IRQ device, we may want
to select a queue for which the response will be handled on the same
or a nearby CPU.  This requires a reverse-map of IRQ affinity.  Add a
notification mechanism to support this.

This is based closely on work by Thomas Gleixner <tglx@linutronix.de>.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Cc: linux-net-drivers@solarflare.com
Cc: Tom Herbert <therbert@google.com>
Cc: David Miller <davem@davemloft.net>
LKML-Reference: <1295470904.11126.84.camel@bwh-desktop>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/interrupt.h |   33 +++++++++++++++++-
 include/linux/irqdesc.h   |    3 ++
 kernel/irq/manage.c       |   82 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 117 insertions(+), 1 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 55e0d42..63c5ad7 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -14,6 +14,8 @@
 #include <linux/smp.h>
 #include <linux/percpu.h>
 #include <linux/hrtimer.h>
+#include <linux/kref.h>
+#include <linux/workqueue.h>
 
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
@@ -240,6 +242,35 @@ extern int irq_can_set_affinity(unsigned int irq);
 extern int irq_select_affinity(unsigned int irq);
 
 extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m);
+
+/**
+ * struct irq_affinity_notify - context for notification of IRQ affinity changes
+ * @irq:		Interrupt to which notification applies
+ * @kref:		Reference count, for internal use
+ * @work:		Work item, for internal use
+ * @notify:		Function to be called on change.  This will be
+ *			called in process context.
+ * @release:		Function to be called on release.  This will be
+ *			called in process context.  Once registered, the
+ *			structure must only be freed when this function is
+ *			called or later.
+ */
+struct irq_affinity_notify {
+	unsigned int irq;
+	struct kref kref;
+	struct work_struct work;
+	void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
+	void (*release)(struct kref *ref);
+};
+
+extern int
+irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify);
+
+static inline void irq_run_affinity_notifiers(void)
+{
+	flush_scheduled_work();
+}
+
 #else /* CONFIG_SMP */
 
 static inline int irq_set_affinity(unsigned int irq, const struct cpumask *m)
@@ -255,7 +286,7 @@ static inline int irq_can_set_affinity(unsigned int irq)
 static inline int irq_select_affinity(unsigned int irq)  { return 0; }
 
 static inline int irq_set_affinity_hint(unsigned int irq,
-                                        const struct cpumask *m)
+					const struct cpumask *m)
 {
 	return -EINVAL;
 }
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index c1a95b7..bfef56d 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -8,6 +8,7 @@
  * For now it's included from <linux/irq.h>
  */
 
+struct irq_affinity_notify;
 struct proc_dir_entry;
 struct timer_rand_state;
 /**
@@ -24,6 +25,7 @@ struct timer_rand_state;
  * @last_unhandled:	aging timer for unhandled count
  * @irqs_unhandled:	stats field for spurious unhandled interrupts
  * @lock:		locking for SMP
+ * @affinity_notify:	context for notification of affinity changes
  * @pending_mask:	pending rebalanced interrupts
  * @threads_active:	number of irqaction threads currently running
  * @wait_for_threads:	wait queue for sync_irq to wait for threaded handlers
@@ -70,6 +72,7 @@ struct irq_desc {
 	raw_spinlock_t		lock;
 #ifdef CONFIG_SMP
 	const struct cpumask	*affinity_hint;
+	struct irq_affinity_notify *affinity_notify;
 #ifdef CONFIG_GENERIC_PENDING_IRQ
 	cpumask_var_t		pending_mask;
 #endif
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0caa59f..0587c5c 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -134,6 +134,10 @@ int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
 		irq_set_thread_affinity(desc);
 	}
 #endif
+	if (desc->affinity_notify) {
+		kref_get(&desc->affinity_notify->kref);
+		schedule_work(&desc->affinity_notify->work);
+	}
 	desc->status |= IRQ_AFFINITY_SET;
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 	return 0;
@@ -155,6 +159,79 @@ int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 }
 EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 
+static void irq_affinity_notify(struct work_struct *work)
+{
+	struct irq_affinity_notify *notify =
+		container_of(work, struct irq_affinity_notify, work);
+	struct irq_desc *desc = irq_to_desc(notify->irq);
+	cpumask_var_t cpumask;
+	unsigned long flags;
+
+	if (!desc)
+		goto out;
+
+	if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))
+		goto out;
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+#ifdef CONFIG_GENERIC_PENDING_IRQ
+	if (desc->status & IRQ_MOVE_PENDING)
+		cpumask_copy(cpumask, desc->pending_mask);
+	else
+#endif
+		cpumask_copy(cpumask, desc->affinity);
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+	notify->notify(notify, cpumask);
+
+	free_cpumask_var(cpumask);
+out:
+	kref_put(&notify->kref, notify->release);
+}
+
+/**
+ *	irq_set_affinity_notifier - control notification of IRQ affinity changes
+ *	@irq:		Interrupt for which to enable/disable notification
+ *	@notify:	Context for notification, or %NULL to disable
+ *			notification.  Function pointers must be initialised;
+ *			the other fields will be initialised by this function.
+ *
+ *	Must be called in process context.  Notification may only be enabled
+ *	after the IRQ is allocated and must be disabled before the IRQ is
+ *	freed using free_irq().
+ */
+int
+irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	struct irq_affinity_notify *old_notify;
+	unsigned long flags;
+
+	/* The release function is promised process context */
+	might_sleep();
+
+	if (!desc)
+		return -EINVAL;
+
+	/* Complete initialisation of *notify */
+	if (notify) {
+		notify->irq = irq;
+		kref_init(&notify->kref);
+		INIT_WORK(&notify->work, irq_affinity_notify);
+	}
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	old_notify = desc->affinity_notify;
+	desc->affinity_notify = notify;
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+	if (old_notify)
+		kref_put(&old_notify->kref, old_notify->release);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
+
 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 /*
  * Generic version of the affinity autoselector.
@@ -1004,6 +1081,11 @@ void free_irq(unsigned int irq, void *dev_id)
 	if (!desc)
 		return;
 
+#ifdef CONFIG_SMP
+	if (WARN_ON(desc->affinity_notify))
+		desc->affinity_notify = NULL;
+#endif
+
 	chip_bus_lock(desc);
 	kfree(__free_irq(irq, dev_id));
 	chip_bus_sync_unlock(desc);

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH net-next-2.6 2/5] lib: cpu_rmap: CPU affinity reverse-mapping
  2011-01-19 21:03 ` [PATCH net-next-2.6 2/5] lib: cpu_rmap: CPU affinity reverse-mapping Ben Hutchings
@ 2011-01-24 23:01   ` David Miller
  0 siblings, 0 replies; 5+ messages in thread
From: David Miller @ 2011-01-24 23:01 UTC (permalink / raw)
  To: bhutchings; +Cc: tglx, netdev, linux-net-drivers, therbert, linux-kernel

From: Ben Hutchings <bhutchings@solarflare.com>
Date: Wed, 19 Jan 2011 21:03:25 +0000

> When initiating I/O on a multiqueue and multi-IRQ device, we may want
> to select a queue for which the response will be handled on the same
> or a nearby CPU.  This requires a reverse-map of IRQ affinity.  Add
> library functions to support a generic reverse-mapping from CPUs to
> objects with affinity and the specific case where the objects are
> IRQs.
> 
> Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

Applied.

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2011-01-24 23:01 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-01-19 20:59 [PATCH net-next-2.6 0/5] RFS hardware acceleration (v3) Ben Hutchings
2011-01-19 21:02 ` [PATCH net-next-2.6 1/5] genirq: Add IRQ affinity notifiers Ben Hutchings
2011-01-22 16:37   ` [tip:irq/numa] " tip-bot for Ben Hutchings
2011-01-19 21:03 ` [PATCH net-next-2.6 2/5] lib: cpu_rmap: CPU affinity reverse-mapping Ben Hutchings
2011-01-24 23:01   ` David Miller

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