lkml.org 
[lkml]   [2006]   [Jun]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Network performance degradation from 2.6.11.12 to 2.6.16.20
    Hi Andi,

    On Mon, Jun 19, 2006 at 05:24:31PM +0200, Andi Kleen wrote:
    >
    > > If you use "pmtmr" try to reboot with kernel option "clock=tsc".
    >
    > That's dangerous advice - when the system choses not to use
    > TSC it often has a reason.
    >
    > >
    > > On my Opteron AMD system i normally can route 400 kpps, but with
    > > timesource "pmtmr" i could only route around 83 kpps. (I found the timer
    > > to be the issue by using oprofile).
    >
    > Unless you're using packet sniffing or any other application
    > that requests time stamps on a socket then the timer shouldn't
    > make much difference. Incoming packets are only time stamped
    > when someone asks for the timestamps.

    I encountered the same problem on a dual core opteron equipped with a
    broadcom NIC (tg3) under 2.4. It could receive 1 Mpps when using TSC
    as the clock source, but the time jumped back and forth, so I changed
    it to 'notsc', then the performance dropped dramatically to around the
    same value as above with one CPU saturated. I suspect that the clock
    precision is needed by the tg3 driver to correctly decide to switch to
    polling mode, but unfortunately, the performance drop rendered the
    solution so much unusable that I finally decided to use it only in
    uniprocessor with TSC enabled.

    > -Andi

    Regards,
    Willy

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-06-26 00:37    [W:3.371 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site