From: Pavel Machek <pavel@ucw.cz>
To: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: Albert Cahalan <acahalan@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: 2048 CPUs [was: Re: New filesystem for Linux]
Date: Tue, 7 Nov 2006 21:26:14 +0000 [thread overview]
Message-ID: <20061107212614.GA6730@ucw.cz> (raw)
In-Reply-To: <Pine.LNX.4.64.0611042332240.20974@artax.karlin.mff.cuni.cz>
Hi!
> >The SGI Altix can have 2048 CPUs.
>
> And does it run one image of Linux? Or more images each
> on few cpus?
>
> How do they solve problem with spinlock livelocks?
>
> If time-spent-outside-spinlock/time-spent-in-spinlock <
> number-of-cpus, the spinlock livelock may happen ---
> this condition is not true normally with 2 or 4 cpus,
> but for that high amount of cpus, there is a danger.
Lets say time-spent-outside-spinlock == time-spent-in-spinlock and
number-of-cpus == 2.
1 < 2 , so it should livelock according to you...
...but afaict this should work okay. Even if spinlocks are very
unfair, as long as time-outside and time-inside comes in big chunks,
it should work.
If you are unlucky, one cpu may stall for a while, but... I see no
livelock.
--
Thanks for all the (sleeping) penguins.
next prev parent reply other threads:[~2006-11-07 21:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <787b0d920611041154l69db46abv4c8c467809ada57c@mail.gmail.com>
2006-11-04 22:36 ` 2048 CPUs [was: Re: New filesystem for Linux] Mikulas Patocka
[not found] ` <787b0d920611050802o460a4000r5ce154e589732a02@mail.gmail.com>
2006-11-06 1:47 ` Mikulas Patocka
2006-11-07 21:26 ` Pavel Machek [this message]
2006-11-07 22:36 ` Mikulas Patocka
2006-11-07 23:14 ` Pavel Machek
2006-11-08 18:26 ` Mikulas Patocka
2006-11-10 9:03 ` Pavel Machek
2006-11-10 15:20 ` Mikulas Patocka
2006-11-10 16:20 ` Alan Cox
2006-11-12 14:28 ` Pavel Machek
2006-11-12 20:07 ` Mikulas Patocka
2006-11-14 6:24 ` Albert Cahalan
2006-11-08 3:04 ` David Chinner
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