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Date: Fri, 13 Jun 2014 23:03:38 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: viro@...iv.linux.org.uk, akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] proc: faster /proc/$PID lookup
Use first character as a hint for /proc/$PID lookup.
Currently it takes one spinlock and search through dozens of
misc proc entries which can not match /proc/$PID.
Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
fs/proc/root.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -199,10 +199,17 @@ static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct
static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
{
- if (!proc_lookup(dir, dentry, flags))
- return NULL;
-
- return proc_pid_lookup(dir, dentry, flags);
+ const char c = dentry->d_name.name[0];
+ struct dentry *rv;
+
+ if ('0' <= c && c <= '9') {
+ rv = proc_pid_lookup(dir, dentry, flags);
+ if (rv)
+ rv = proc_lookup(dir, dentry, flags);
+ } else {
+ rv = proc_lookup(dir, dentry, flags);
+ }
+ return rv;
}
static int proc_root_readdir(struct file *file, struct dir_context *ctx)
--
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