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From: Kip Macy <kmacy@netapp.com>
To: ognen@gene.pbi.nrc.ca
Cc: linux-kernel@vger.kernel.org
Subject: Re: threading question
Date: Tue, 12 Jun 2001 12:15:01 -0700 (PDT)	[thread overview]
Message-ID: <Pine.GSO.4.10.10106121214380.20809-100000@orbit-fe.eng.netapp.com> (raw)
In-Reply-To: <Pine.LNX.4.30.0106121304320.24593-100000@gene.pbi.nrc.ca>

For heavy threading, try a user-level threads package.

		-Kip


On Tue, 12 Jun 2001 ognen@gene.pbi.nrc.ca wrote:

> 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
> 
> -
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> 


  reply	other threads:[~2001-06-12 19:16 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
2001-06-12 19:15     ` Kip Macy [this message]
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

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