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From: bert hubert <ahu@ds9a.nl>
To: linux-kernel@vger.kernel.org
Subject: Re: threading question
Date: Wed, 13 Jun 2001 19:31:39 +0200	[thread overview]
Message-ID: <20010613193139.A10072@home.ds9a.nl> (raw)
In-Reply-To: <Pine.LNX.4.30.0106121213570.24593-100000@gene.pbi.nrc.ca> <Pine.GSO.4.10.10106121200330.20809-100000@orbit-fe.eng.netapp.com>
In-Reply-To: <Pine.GSO.4.10.10106121200330.20809-100000@orbit-fe.eng.netapp.com>; from kmacy@netapp.com on Tue, Jun 12, 2001 at 12:06:40PM -0700

On Tue, Jun 12, 2001 at 12:06:40PM -0700, Kip Macy wrote:
> This may sound like flamebait, but its not. Linux threads are basically
> just processes that share the same address space. Their performance is
> measurably worse than it is on most commercial Unixes and FreeBSD.

Thread creation may be a bit slow. But the kludges to provide posix threads
completely from userspace also hurt. Notably, they do not scale over
multiple CPUs.

> They are not, or at least two years ago, were not POSIX compliant
> (they behaved badly with respect to signals). The impoverished

POSIX threads are silly with respect to signals. I do almost all my
programming these days with pthreads and I find that I really do not miss
signals at all.

> from Larry McVoy's home page attributed to Alan Cox illustrates this
> reasonably well: "A computer is a state machine. Threads are for people
> who can't program state machines." Sorry for not being more helpful.

I got that response too. When I pressed kernel people for details it turns
out that they think having hundreds of runnable threads/processes (mostly
the same thing under Linux) is wasteful. The scheduler is just not optimised
for that.

Regards,

bert

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  parent reply	other threads:[~2001-06-13 17:33 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
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 [this message]
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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