LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
To: herbert@gondor.apana.org.au
Cc: LKML <linux-kernel@vger.kernel.org>, netdev@vger.kernel.org
Subject: tbench regression in 2.6.25-rc1
Date: Fri, 15 Feb 2008 09:52:01 +0800	[thread overview]
Message-ID: <1203040321.3027.131.camel@ymzhang> (raw)

Comparing with kernel 2.6.24, tbench result has regression with
2.6.25-rc1.

1) On 2 quad-core processor stoakley: 4%.
2) On 4 quad-core processor tigerton: more than 30%.

bisect located below patch.

b4ce92775c2e7ff9cf79cca4e0a19c8c5fd6287b is first bad commit
commit b4ce92775c2e7ff9cf79cca4e0a19c8c5fd6287b
Author: Herbert Xu <herbert@gondor.apana.org.au>
Date:   Tue Nov 13 21:33:32 2007 -0800

    [IPV6]: Move nfheader_len into rt6_info
    
    The dst member nfheader_len is only used by IPv6.  It's also currently
    creating a rather ugly alignment hole in struct dst.  Therefore this patch
    moves it from there into struct rt6_info.


As tbench uses ipv4, so the patch's real impact on ipv4 is it deletes
nfheader_len in dst_entry. It might change cache line alignment.

To verify my finding, I just added nfheader_len back to dst_entry in 2.6.25-rc1
and reran tbench on the 2 machines. Performance could be recovered completely.

I started cpu_number*2 tbench processes. On my 16-core tigerton:
#./tbench_srv &
#./tbench 32 127.0.0.1

-yanmin



             reply	other threads:[~2008-02-15  1:53 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-15  1:52 Zhang, Yanmin [this message]
2008-02-15  6:05 ` Eric Dumazet
2008-02-15  6:30   ` Zhang, Yanmin
2008-02-15 14:21     ` Eric Dumazet
2008-02-15 23:22       ` David Miller
2008-02-18  8:12         ` Zhang, Yanmin
2008-02-18 10:11           ` Eric Dumazet
2008-02-19  2:44             ` Zhang, Yanmin
2008-02-19  7:35               ` Eric Dumazet
2008-02-19  8:40                 ` Zhang, Yanmin
2008-02-18 17:33           ` Valdis.Kletnieks
2008-02-19  6:51             ` Zhang, Yanmin
2008-02-19  7:40               ` Eric Dumazet
2008-02-20  7:04                 ` Zhang, Yanmin
2008-02-20  7:38                   ` Eric Dumazet
2008-02-20  8:14                     ` David Miller
2008-02-20  8:41                       ` Zhang, Yanmin
2008-02-18  1:39       ` Zhang, Yanmin

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1203040321.3027.131.camel@ymzhang \
    --to=yanmin_zhang@linux.intel.com \
    --cc=herbert@gondor.apana.org.au \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --subject='Re: tbench regression in 2.6.25-rc1' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).