public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: richard <yang.lu@archermind.com>
To: linux-kernel@vger.kernel.org
Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org
Subject: kernel  performance issue
Date: Thu, 31 Jul 2008 18:38:06 +0800	[thread overview]
Message-ID: <4891960E.2000605@archermind.com> (raw)

Hi:

I have a question about the kernel performance of kernel 2.6.24. I use
"time"
to account the time cost of "date" execution, and find that the "real time"
of kernel 2.6.24 is always bigger than kernel 2.6.21 on my arm board.
For my
understanding, the time cost of 2.6.24 shouldn't be bigger than 2.6.21,
because
it is a upgrade of 2.6.21 and the its performance should be better than
2.6.21,
if I am wrong please let me know.


[root@Linux /root]#cat ./date-loop.sh
#! /bin/sh
loop=1
while [ $loop -le 50 ]
do
         date +%s
         loop=$(($loop+1))
done


Time cost in kernel 2.6.24:
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.06s
sys     0m 0.43s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.07s
sys     0m 0.42s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.09s
sys     0m 0.40s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.07s
sys     0m 0.41s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.07s
sys     0m 0.42s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.09s
sys     0m 0.40s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.06s
sys     0m 0.43s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.08s
sys     0m 0.41s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.09s
sys     0m 0.40s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.10s
sys     0m 0.39s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.05s
sys     0m 0.44s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.05s
sys     0m 0.44s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.09s
sys     0m 0.40s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.07s
sys     0m 0.42s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.07s
sys     0m 0.42s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.48s
user    0m 0.09s
sys     0m 0.40s
[root@Linux /root]#

Time cost in kernel 2.6.21:
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.08s
sys     0m 0.38s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.07s
sys     0m 0.39s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.09s
sys     0m 0.37s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.09s
sys     0m 0.37s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.08s
sys     0m 0.38s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.06s
sys     0m 0.40s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.09s
sys     0m 0.37s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.10s
sys     0m 0.36s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.04s
sys     0m 0.42s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.09s
sys     0m 0.37s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.07s
sys     0m 0.39s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.08s
sys     0m 0.38s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.10s
sys     0m 0.36s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.09s
sys     0m 0.37s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.09s
sys     0m 0.37s
[root@Linux /root]#time ./date-loop.sh > /dev/null
real    0m 0.45s
user    0m 0.07s
sys     0m 0.39s
[root@Linux /root]#

-- 






Best Regards,
Yang Lu


                 reply	other threads:[~2008-07-31 10:53 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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=4891960E.2000605@archermind.com \
    --to=yang.lu@archermind.com \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=torvalds@linux-foundation.org \
    /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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox