linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Sasha Pachev <sasha@mysql.com>
To: linux-kernel@vger.kernel.org
Subject: Strange thread behaviour on 8-way x86 machine
Date: Tue, 3 Jul 2001 12:25:12 -0600	[thread overview]
Message-ID: <0107031225120K.18621@mysql> (raw)

Hi,

I have observed a rather strange behaviour doing a multi-threaded CPU 
benchmark on an 8-way machine running 2.4.2 SMP kernel. Even when the 
priority is reniced to the highest possible value, I am still unable to reach 
more than 50% CPU utilization. My benchmark just creates a bunch of threads 
with pthread_create(), and then runs a simple integer computation in each 
thread. On a dual with 2.4.3 kernel, and a 4-way with 2.4.2 kernel, I am able 
to reach full CPU utilization. 

At first glance, it appears to be like some overzealous fairness problem in 
the scheduler that is exhibited only when you have more than 4 CPUs. Before I 
start scrutinizing the source trying to understand the inner workings of the 
scheduler, I would like to get some feedback from people that know something 
about the subject. Any ideas/suggestions would be appreciated.

-- 
MySQL Development Team
For technical support contracts, visit https://order.mysql.com/
   __  ___     ___ ____  __ 
  /  |/  /_ __/ __/ __ \/ /   Sasha Pachev <sasha@mysql.com>
 / /|_/ / // /\ \/ /_/ / /__  MySQL AB, http://www.mysql.com/
/_/  /_/\_, /___/\___\_\___/  Provo, Utah, USA
       <___/                  

             reply	other threads:[~2001-07-03 18:24 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-07-03 18:25 Sasha Pachev [this message]
2001-07-03 18:51 ` Strange thread behaviour on 8-way x86 machine Mike Kravetz
2001-07-06 18:45   ` Sasha Pachev
2001-07-06 19:24     ` Rik van Riel
2001-07-06 20:35       ` Sasha Pachev
2001-07-06 20:41         ` Rik van Riel

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=0107031225120K.18621@mysql \
    --to=sasha@mysql.com \
    --cc=linux-kernel@vger.kernel.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;
as well as URLs for NNTP newsgroup(s).