lkml.org 
[lkml]   [2001]   [Jun]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: threading question
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
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:55    [W:0.112 / U:1.748 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site