From: Andrea Arcangeli <andrea@novell.com>
To: Arjan van de Ven <arjanv@redhat.com>
Cc: Hugh Dickins <hugh@veritas.com>,
"Martin J. Bligh" <mbligh@aracnet.com>,
Andrea Arcangeli <andrea@suse.de>,
Alan Cox <alan@lxorguk.ukuu.org.uk>, Chris Wedgwood <cw@f00f.org>,
LKML <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 1/3] Separate IRQ-stacks from 4K-stacks option
Date: Sun, 12 Sep 2004 16:17:01 +0200 [thread overview]
Message-ID: <20040912141701.GA21626@nocona.random> (raw)
In-Reply-To: <20040910153421.GD24434@devserv.devel.redhat.com>
On Fri, Sep 10, 2004 at 05:34:21PM +0200, Arjan van de Ven wrote:
> disabling is actually not a bad idea; hard irq handlers run for a very short
you mean hard irq handlers "should run" for a very short time. There can
be slow hardware that needs a long time, and fast hardware that needs a
short time, and in turn it makes perfect sense to allow nesting to give
low latency to the "fast" onces, like it has always happened so far (not
only in linux AFIK). Disabling nesting completely sounds a very bad
idea to me, when "limiting nesting" can be achieved easily as confirmed
by Alan too.
> time, but when they nest you effectively have like a semi context switch in
> the middle of the work so performance suffers...
It's not nearly a semi context switch, it's like the timer irq that runs
on top of userspace, not nearly the cost of a context switch (no time
wasted calling the scheduler or the softirqs either for obvious reasons).
next prev parent reply other threads:[~2004-09-12 14:20 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-09 23:25 [PATCH 1/3] Separate IRQ-stacks from 4K-stacks option Chris Wedgwood
2004-09-09 23:55 ` Brian Gerst
2004-09-09 23:59 ` Chris Wedgwood
2004-09-10 6:40 ` Arjan van de Ven
2004-09-10 6:45 ` Chris Wedgwood
2004-09-10 6:52 ` Arjan van de Ven
2004-09-10 7:15 ` Chris Wedgwood
2004-09-10 7:21 ` Arjan van de Ven
2004-09-10 7:23 ` Chris Wedgwood
2004-09-10 7:35 ` Arjan van de Ven
2004-09-10 9:12 ` Alan Cox
2004-09-10 9:14 ` Alan Cox
2004-09-10 10:27 ` Russell King
2004-09-10 14:30 ` Martin J. Bligh
2004-09-10 15:06 ` Chris Wedgwood
2004-09-10 15:07 ` Hugh Dickins
2004-09-10 15:12 ` Alan Cox
2004-09-10 15:15 ` Arjan van de Ven
2004-09-10 15:28 ` Andrea Arcangeli
2004-09-10 15:09 ` Alan Cox
2004-09-10 15:34 ` Arjan van de Ven
2004-09-12 14:17 ` Andrea Arcangeli [this message]
2004-09-12 15:03 ` Martin J. Bligh
2004-09-12 15:45 ` Zwane Mwaikambo
2004-09-12 16:00 ` Martin J. Bligh
2004-10-20 16:27 ` Lee Revell
2004-10-21 15:18 ` Zwane Mwaikambo
2004-09-12 19:18 ` Lee Revell
2004-09-12 19:25 ` Chris Wedgwood
2004-09-12 19:35 ` Ingo Molnar
2004-09-12 19:40 ` Chris Wedgwood
2004-09-12 19:44 ` Ingo Molnar
2004-09-12 20:33 ` Andrea Arcangeli
2004-09-12 21:36 ` Lee Revell
2004-09-12 22:07 ` Andrea Arcangeli
2004-09-12 22:25 ` Lee Revell
2004-09-13 6:16 ` Ingo Molnar
2004-09-13 7:27 ` Lee Revell
2004-09-15 19:43 ` Bill Davidsen
2004-09-15 19:51 ` Andrea Arcangeli
2004-09-15 20:00 ` Ingo Molnar
2004-09-15 20:39 ` Lee Revell
2004-10-20 17:50 ` Timothy Miller
2004-09-13 7:32 ` Jens Axboe
2004-09-13 10:31 ` Andrea Arcangeli
2004-09-13 10:34 ` Arjan van de Ven
2004-09-13 12:30 ` Jens Axboe
2004-10-20 17:46 ` Timothy Miller
2004-09-13 10:51 ` Alan Cox
2004-09-13 20:26 ` Bill Davidsen
2004-09-14 5:20 ` Lee Revell
2004-10-20 15:46 ` Timothy Miller
2004-10-20 15:35 ` Arjan van de Ven
2004-10-20 16:39 ` Lee Revell
2004-10-20 16:50 ` Andrea Arcangeli
2004-10-20 16:55 ` Lee Revell
2004-10-20 17:08 ` Andrea Arcangeli
2004-10-20 17:15 ` Lee Revell
2004-10-20 17:34 ` Andrea Arcangeli
2004-10-20 17:58 ` Timothy Miller
2004-10-20 17:55 ` Lee Revell
2004-10-20 18:25 ` Timothy Miller
2004-10-20 18:28 ` Lee Revell
2004-10-20 18:51 ` Alan Cox
2004-10-20 23:19 ` Lee Revell
2004-09-10 15:16 ` Martin J. Bligh
2004-10-20 15:43 ` Timothy Miller
2004-10-20 15:35 ` Arjan van de Ven
2004-09-10 15:58 ` Alexander E. Patrakov
2004-09-10 16:19 ` Nathan Bryant
2004-09-10 17:54 ` Martin J. Bligh
2004-09-10 17:54 ` Bill Davidsen
2004-09-10 9:27 ` Alan Cox
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