linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: <ognen@gene.pbi.nrc.ca>
To: Christoph Hellwig <hch@ns.caldera.de>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: threading question
Date: Tue, 12 Jun 2001 13:07:11 -0600 (CST)	[thread overview]
Message-ID: <Pine.LNX.4.30.0106121304320.24593-100000@gene.pbi.nrc.ca> (raw)
In-Reply-To: <200106121858.f5CIwmX05650@ns.caldera.de>

Hello,

due to the nature of the problem (a pairwise mutual alignment of n
sequences results in mx. n^2 alignments which can each be done in a
separate thread), I need to create and destroy the threads frequently.

I am not really comfortable with 1.4 - 1.5 speedups since the solution was
intended as a Linux one primarily and it just happenned that it works (and
now even better) on Solaris/SGI/OSF...

Best regards,
Ognen

On Tue, 12 Jun 2001, Christoph Hellwig wrote:

> In article <Pine.LNX.4.30.0106121213570.24593-100000@gene.pbi.nrc.ca> you wrote:
> > On dual-CPU machines the speedups are as follows: my version
> > is 1.88 faster than the sequential one on IRIX, 1.81 times on Solaris,
> > 1.8 times on OSF/1, 1.43 times on Linux 2.2.x and 1.52 times on Linux 2.4
> > kernel. Why are the numbers on Linux machines so much lower?
>
> Does your measurement include the time needed to actually create the
> threads or do you even frequently create and destroy threads?
>
> The code for creating threads is _horribly_ slow in Linuxthreads due
> to the way it is implemented.
>
> > It is the
> > same multi-threaded code, I am not using any tricks, the code basically
> > uses PTHREAD_CREATE_DETACHED and PTHREAD_SCOPE_SYSTEM and the thread stack
> > size is set to 8K (but the numbers are the same with larger/smaller stack
> > sizes).
> >
> > Is there anything I am missing? Is this to be expected due to Linux way of
> > handling threads (clone call)? I am just trying to explain the numbers and
> > nothing else comes to mind....
>
> Linuxthreads is a rather bad pthreads implementation performance-wise,
> mostly due to the rather different linux-native threading model.
>
> 	Christoph


  reply	other threads:[~2001-06-12 19:08 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-06-12 18:24 ognen
2001-06-12 18:39 ` Davide Libenzi
2001-06-12 18:57 ` from dmesg: kernel BUG at inode.c:486 Olivier Sessink
2001-06-12 18:58 ` threading question Christoph Hellwig
2001-06-12 19:07   ` ognen [this message]
2001-06-12 19:15     ` Kip Macy
2001-06-12 19:29       ` Christoph Hellwig
2001-06-12 19:15     ` Christoph Hellwig
2001-06-13 12:20     ` Kurt Garloff
2001-06-13 13:35       ` J . A . Magallon
2001-06-13 14:17         ` Philips
2001-06-13 15:06           ` ognen
2001-06-12 21:44   ` Davide Libenzi
2001-06-12 21:48     ` ognen
2001-06-14 18:15       ` Alan Cox
2001-06-14 22:42         ` threading question (results after thread pooling) ognen
2001-06-14 23:00           ` Mike Castle
2001-06-12 21:58     ` threading question Albert D. Cahalan
2001-06-12 23:48       ` J . A . Magallon
2001-06-12 19:06 ` Kip Macy
2001-06-12 19:14   ` Alexander Viro
2001-06-12 19:25     ` Russell Leighton
2001-06-12 23:27       ` Mike Castle
2001-06-13 17:31   ` bert hubert
2001-06-14  6:45     ` Helge Hafting
2001-06-14 18:28   ` Alan Cox
2001-06-14 19:01     ` bert hubert
2001-06-14 19:22       ` Russell Leighton
2001-06-15 11:29       ` Anil Kumar
2001-06-14 23:05     ` J . A . Magallon
2001-06-16 14:16     ` Michael Rothwell
2001-06-16 15:19       ` Alan Cox
2001-06-16 18:33         ` Russell Leighton
2001-06-16 19:06         ` Michael Rothwell
2001-06-16 21:30           ` Coroutines [was Re: threading question] Russell Leighton
2001-06-12 22:41 ` threading question Pavel Machek
2001-06-13 19:05 Hubertus Franke
     [not found] <fa.f6da6av.agod3u@ifi.uio.no>
     [not found] ` <fa.e54jbkv.kg4r99@ifi.uio.no>
2001-06-16 22:22   ` Dan Maas

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=Pine.LNX.4.30.0106121304320.24593-100000@gene.pbi.nrc.ca \
    --to=ognen@gene.pbi.nrc.ca \
    --cc=hch@ns.caldera.de \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: threading question' \
    /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).