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From: Alexey Dobriyan <adobriyan@gmail.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org, Alexey Dobriyan <adobriyan@gmail.com>
Subject: [PATCH 10/13] proc: convert readdir /proc to _print_integer()
Date: Tue, 28 Aug 2018 02:15:00 +0300
Message-ID: <20180827231503.26899-10-adobriyan@gmail.com> (raw)
In-Reply-To: <20180827231503.26899-1-adobriyan@gmail.com>

Benchmark readdir("/proc") 2^13 times with 2K processes in a pid
namespace:

	850.3750 us per readdir
	786.5625

	-7.5%

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
 fs/proc/base.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 79d2f7d72ad1..33f444721965 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3223,16 +3223,15 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx)
 	for (iter = next_tgid(ns, iter);
 	     iter.task;
 	     iter.tgid += 1, iter = next_tgid(ns, iter)) {
-		char name[10 + 1];
-		unsigned int len;
+		char name[10], *p = name + sizeof(name);
 
 		cond_resched();
 		if (!has_pid_permissions(ns, iter.task, HIDEPID_INVISIBLE))
 			continue;
 
-		len = snprintf(name, sizeof(name), "%u", iter.tgid);
+		p = _print_integer_u32(p, iter.tgid);
 		ctx->pos = iter.tgid + TGID_OFFSET;
-		if (!proc_fill_cache(file, ctx, name, len,
+		if (!proc_fill_cache(file, ctx, p, name + sizeof(name) - p,
 				     proc_pid_instantiate, iter.task, NULL)) {
 			put_task_struct(iter.task);
 			return 0;
-- 
2.16.4


  parent reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-27 23:14 [PATCH 01/13] seq_file: rewrite seq_puts() in terms of seq_write() Alexey Dobriyan
2018-08-27 23:14 ` [PATCH 02/13] proc: apply seq_puts() whenever possible Alexey Dobriyan
2018-08-27 23:14 ` [PATCH 03/13] proc: rename "p" variable in proc_readfd_common() Alexey Dobriyan
2018-08-27 23:14 ` [PATCH 04/13] proc: rename "p" variable in proc_map_files_readdir() Alexey Dobriyan
2018-08-27 23:14 ` [PATCH 05/13] proc: new and improved way to print decimals Alexey Dobriyan
2018-08-27 23:14 ` [PATCH 06/13] proc: convert /proc/self to _print_integer() Alexey Dobriyan
2018-08-29  9:50   ` David Laight
2018-08-30 13:13     ` Alexey Dobriyan
2018-08-27 23:14 ` [PATCH 07/13] proc: convert /proc/thread-self " Alexey Dobriyan
2018-08-27 23:14 ` [PATCH 08/13] proc: convert /proc/*/fd " Alexey Dobriyan
2018-08-27 23:14 ` [PATCH 09/13] proc: convert dentry flushing on exit " Alexey Dobriyan
2018-08-27 23:15 ` Alexey Dobriyan [this message]
2018-08-27 23:15 ` [PATCH 11/13] proc: readdir /proc/*/task Alexey Dobriyan
2018-08-28 12:36   ` Ahmed S. Darwish
2018-08-28 13:04     ` Ahmed S. Darwish
2018-08-28 19:35       ` Alexey Dobriyan
2018-08-29 23:43         ` Andrew Morton
2018-08-30 13:20           ` Alexey Dobriyan
2018-08-28 19:31     ` Alexey Dobriyan
2018-08-27 23:15 ` [PATCH 12/13] proc: convert /proc/*/statm to _print_integer() Alexey Dobriyan
2018-08-27 23:15 ` [PATCH 13/13] proc: convert /proc/*/task/*/children " Alexey Dobriyan
2018-08-28 18:24 ` [PATCH 01/13] seq_file: rewrite seq_puts() in terms of seq_write() Joe Perches
2018-08-28 20:48   ` Joe Perches
2018-09-03 14:17 ` Alexey Dobriyan

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