lkml.org 
[lkml]   [2008]   [May]   [8]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateThu, 8 May 2008 16:33:40 -0700 (PDT)
FromLinus Torvalds <>
SubjectRe: [patch] speed up / fix the new generic semaphore code (fix AIM7 40% regression with 2.6.26-rc1)

On Fri, 9 May 2008, Alan Cox wrote:
> 
> I don't think fixing n_tty is now a big job if someone wants to take a
> swing at it. The driver write/throttle/etc routines below the n_tty ldisc
> layer are now BKL clean so it should just be the internal locking of the
> buffers, window and the like to tackle.

Well, it turns out that Ingo's fixed statistics actually put the real cost 
in fcntl/ioctl/open/release:

    310  down <= lock_kernel <= sys_fcntl <= system_call_after_swapgs <
    332  down <= lock_kernel <= vfs_ioctl <= do_vfs_ioctl <
    380  down <= lock_kernel <= tty_release <= __fput <
    422  down <= lock_kernel <= chrdev_open <= __dentry_open <

rather than the write routines. But it may be that Ingo was just profiling 
two different sections, and it's really all of them.

			Linus


\
 
 \ /
  Last update: 2008-05-09 01:37    [from the cache]
©2003-2008