From: Arjan van de Ven <arjanv@redhat.com>
To: Mark Gross <mgross@linux.co.intel.com>
Cc: Tim Bird <tim.bird@am.sony.com>,
root@chaos.analogic.com,
linux kernel <linux-kernel@vger.kernel.org>
Subject: Re: Why no interrupt priorities?
Date: Fri, 27 Feb 2004 08:14:45 +0100 [thread overview]
Message-ID: <20040227071445.GA5695@devserv.devel.redhat.com> (raw)
In-Reply-To: <200402261421.34885.mgross@linux.intel.com>
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On Thu, Feb 26, 2004 at 02:21:34PM -0800, Mark Gross wrote:
> > hardware IRQ priorities are useless for the linux model. In linux, the
> > hardirq runs *very* briefly and then lets the softirq context do the
> > longer taking work. hardware irq priorities then don't matter really
> > because the hardirq's are hardly ever interrupted really, and when they
> > are they cause a performance *loss* due to cache trashing. The latency
> > added by waiting briefly is going to be really really short for any sane
> > hardware.
>
> Keep in mind the context is Linux running on non-sane hardware, sloooow CPUs,
50Mhz is already really really fast in this context.
> latency sensitive small io buffers etc. Losing system wide throughput to have
> the hardware codec not be starved is a happy trade off to make.
The point I tried to make was that it would INCREASE latency. Unless you
have misdesigned device drivers, which is something that is fixable :)
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next prev parent reply other threads:[~2004-02-27 7:14 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-26 19:05 Why no interrupt priorities? Tim Bird
2004-02-26 19:39 ` Richard B. Johnson
2004-02-26 21:02 ` Tim Bird
2004-02-26 21:30 ` Arjan van de Ven
2004-02-26 22:21 ` Mark Gross
2004-02-27 7:14 ` Arjan van de Ven [this message]
2004-02-27 11:27 ` Ingo Oeser
2004-02-27 11:52 ` Arjan van de Ven
2004-02-27 13:23 ` Richard B. Johnson
2004-02-27 12:04 ` Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2004-02-26 23:47 Albert Cahalan
2004-02-27 1:36 Grover, Andrew
2004-02-27 3:02 ` Randy.Dunlap
2004-02-29 8:32 ` Michael Frank
2004-02-29 8:36 ` Arjan van de Ven
2004-02-29 9:52 ` Michael Frank
2004-02-27 5:32 ` Benjamin Herrenschmidt
2004-02-27 6:26 ` Michael Frank
2004-02-27 6:46 ` Benjamin Herrenschmidt
2004-02-27 9:05 ` Russell King
2004-02-27 13:31 ` Michael Frank
2004-02-27 13:45 ` Richard B. Johnson
2004-02-27 13:50 ` Russell King
2004-02-27 14:51 ` Michael Frank
2004-02-27 7:25 ` Arjan van de Ven
2004-02-27 10:15 ` Helge Hafting
2004-02-27 18:32 ` Mike Fedyk
[not found] <mailman.1077822002.21081.linux-kernel2news@redhat.com>
2004-02-27 8:00 ` Pete Zaitcev
2004-02-27 11:37 Etienne Lorrain
2004-02-27 13:24 ` Michael Frank
2004-02-27 17:44 Grover, Andrew
2004-02-27 18:15 ` Chris Friesen
2004-02-27 18:42 ` Richard B. Johnson
2004-02-27 19:42 ` Michael Frank
2004-02-27 19:11 ` Michael Frank
2004-02-27 18:55 ` Matt Mackall
2004-02-27 19:09 ` Tim Hockin
2004-02-27 20:29 ` Matt Mackall
2004-02-27 19:19 ` Michael Frank
2004-02-27 20:53 ` Jesse Pollard
2004-02-29 9:43 ` Michael Frank
2004-03-01 16:57 ` Jesse Pollard
2004-03-01 17:35 ` Michael Frank
2004-03-02 15:25 ` Jesse Pollard
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