lkml.org 
[lkml]   [2008]   [May]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    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    [W:0.040 / U:36.760 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site