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Date: Wed, 7 Mar 2012 10:55:25 +0800 From: Feng Tang <feng.tang@...el.com> To: Jason Wang <jasowang@...hat.com> Cc: David Miller <davem@...emloft.net>, alex.shi@...el.com, eric.dumazet@...il.com, linux-kernel@...r.kernel.org, tim.c.chen@...el.com, ying.huang@...el.com, netdev@...r.kernel.org Subject: Re: 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@...el.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 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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