lkml.org 
[lkml]   [2012]   [Mar]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: TCP_STREAM performance regression on commit b3613118
    On Tue, Mar 06, 2012 at 04:26:13PM +0800, Jason Wang wrote:
    > On 03/06/2012 04:11 PM, Feng Tang wrote:
    > >On Thu, Mar 01, 2012 at 10:07:43PM -0500, David Miller wrote:
    > >>> From: Alex Shi<alex.shi@intel.com>
    > >>> Date: Fri, 02 Mar 2012 10:45:17 +0800
    > >>>
    > >>>> > Add CC to tang feng, He is working on this issue.
    > >>> > Is he? I'm pretty sure this is due to the TCP receive
    > >>window growing
    > >>> issue Eric Dumazet, Neal Cardwell and I are discussing in the thread
    > >>> starting at:
    > >>> > http://marc.info/?l=linux-netdev&m=132916352815286&w=2
    > >Yes, probably, as we did find some clue related with the tcp_r/wmem.
    > >
    > >Here is the regression we found:
    > >On some machines, we found there is about 10% resgression of netperf
    > >TCP-64K loopback test between 3.2 and 3.3-rc1. The exact test is:
    > >./netperf -t TCP_STREAM -l 60 -H 127.0.0.1 -i 50,3 -I 99,5 -- -s 32768 -S 32768 -m 4096
    > >
    > >
    > >The test machine is a 2 socket Quad Core Core 2 Duo server(2.66GHz) with
    > >8 GB RAM. Following are the debug info (ifconfig/netstat -s/tcp_rwmem)
    > >before and after the test:
    > >
    > >The most obvious differences I can see are:
    > >1) 311 GB vs 241 GB from ifconfig
    > >2) the difference of the tcp_r/wmem
    >
    > Hi:
    >
    > Could you try the newest kernel? Looks like the difference has been
    > already fixed by commit c43b874d5d714f271b80d4c3f49e05d0cbf51ed2.

    Yeah, with the newest kernel, the regression of this simple test is gone,
    the performance difference with 3.2 kernel is now only about 1-2%. Thanks
    for the info.

    - Feng

    >
    > Thanks


    \
     
     \ /
      Last update: 2012-03-07 03:59    [W:0.022 / U:91.772 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site