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From: Ingo Molnar <mingo@elte.hu>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: linux-kernel@vger.kernel.org, Alan.Brunelle@hp.com,
	arjan@linux.intel.com, dgc@sgi.com, npiggin@suse.de
Subject: Re: [PATCH 4/8] x86: add support for remotely triggering the block softirq
Date: Thu, 7 Feb 2008 11:38:04 +0100	[thread overview]
Message-ID: <20080207103804.GE16735@elte.hu> (raw)
In-Reply-To: <20080207103136.GG15220@kernel.dk>


* Jens Axboe <jens.axboe@oracle.com> wrote:

> > pick up the threaded softirq patches from -rt, those move all 
> > softirqs processing into kernel threads. I'd suggest to extend those 
> > via wakeup-from-remote functionality - it fits the construct quite 
> > naturally. You should also be able to directly observe any 
> > performance impact of threaded softirq handlers. (and if you find 
> > any, let me know so that we can make it faster :-)
> 
> I was just considering that, since I knew -rt moved the softirqs into 
> threads. I'll look into it, but may not post anything until after my 
> vacation.

we should more seriously investigate kernel thread scalability for 
another reason as well: besides -rt, any generic async IO facility we 
pick up will likely heavily rely on them. Kernel thread scheduling is 
quite a bit lighter than user task scheduling [no TLB flushes, etc.] - 
and if it is still not good enough we could probably accelerate them 
some more. (and everyone will benefit) irq-context softirqs on the other 
hand are quite rigid and bring in many atomicity assumptions so they are 
not as natural to program for.

	Ingo

  reply	other threads:[~2008-02-07 10:38 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-07  9:18 [PATCH 0/8] IO queuing and complete affinity Jens Axboe
2008-02-07  9:18 ` [PATCH 1/8] block: split softirq handling into blk-softirq.c Jens Axboe
2008-02-07  9:18 ` [PATCH 2/8] Add interface for queuing work on a specific CPU Jens Axboe
2008-02-07  9:45   ` Andrew Morton
2008-02-07  9:49     ` Jens Axboe
2008-02-07 17:44       ` Harvey Harrison
2008-02-11 10:51     ` Oleg Nesterov
2008-02-07  9:19 ` [PATCH 3/8] block: make kblockd_schedule_work() take the queue as parameter Jens Axboe
2008-02-07  9:19 ` [PATCH 4/8] x86: add support for remotely triggering the block softirq Jens Axboe
2008-02-07 10:07   ` Ingo Molnar
2008-02-07 10:17     ` Jens Axboe
2008-02-07 10:25       ` Ingo Molnar
2008-02-07 10:31         ` Jens Axboe
2008-02-07 10:38           ` Ingo Molnar [this message]
2008-02-07 14:18             ` Jens Axboe
2008-02-07 10:49           ` [patch] block layer: kmemcheck fixes Ingo Molnar
2008-02-07 17:42             ` Linus Torvalds
2008-02-07 17:55               ` Jens Axboe
2008-02-07 19:31               ` Ingo Molnar
2008-02-07 20:06                 ` Jens Axboe
2008-02-08  1:22               ` David Miller
2008-02-08  1:28                 ` Linus Torvalds
2008-02-08 15:09                 ` Arjan van de Ven
2008-02-08 22:44                   ` Nick Piggin
2008-02-08 22:56                     ` Arjan van de Ven
2008-02-08 23:58                       ` Nick Piggin
2008-02-08 11:38               ` Jens Axboe
2008-02-07  9:19 ` [PATCH 5/8] x86-64: add support for remotely triggering the block softirq Jens Axboe
2008-02-07  9:19 ` [PATCH 6/8] ia64: " Jens Axboe
2008-02-07  9:19 ` [PATCH 7/8] kernel: add generic softirq interface for triggering a remote softirq Jens Axboe
2008-02-07  9:19 ` [PATCH 8/8] block: add test code for testing CPU affinity Jens Axboe
2008-02-07 15:16 ` [PATCH 0/8] IO queuing and complete affinity Alan D. Brunelle
2008-02-07 18:25 ` IO queuing and complete affinity with threads (was Re: [PATCH 0/8] IO queuing and complete affinity) Jens Axboe
2008-02-07 20:40   ` Alan D. Brunelle
2008-02-08  7:38   ` Nick Piggin
2008-02-08  7:47     ` Jens Axboe
2008-02-08  7:53       ` Nick Piggin
2008-02-08  7:59         ` Jens Axboe
2008-02-08  8:12           ` Nick Piggin
2008-02-08  8:24             ` Jens Axboe
2008-02-08  8:33               ` Nick Piggin
2008-02-11  5:22           ` David Chinner
2008-02-12  8:28             ` Jeremy Higdon

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