Messages in this thread | | | Date | Tue, 12 Jun 2001 12:15:01 -0700 (PDT) | From | Kip Macy <> | Subject | Re: threading question |
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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/ >
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