From: Ingo Molnar <mingo@elte.hu>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: linux-kernel@vger.kernel.org, npiggin@suse.de, paulus@samba.org,
tglx@linutronix.de, mingo@redhat.com, tony.luck@intel.com
Subject: Re: [PATCH 0/5] Generic smp_call_function(), improvements, and smp_call_function_single()
Date: Thu, 27 Mar 2008 11:08:02 +0100 [thread overview]
Message-ID: <20080327100802.GD15003@elte.hu> (raw)
In-Reply-To: <20080321131558.GA15355@kernel.dk>
* Jens Axboe <jens.axboe@oracle.com> wrote:
> which is pretty much identical to io-cpu-affinity, except it uses
> kernel threads for completion.
>
> The reason why I dropped the kthread approach is that it was slower.
> Time from signal to run was about 33% faster with IPI than with
> wake_up_process(). Doing benchmark runs, and the IPI approach won
> hands down in cache misses as well.
with irq threads we'll have all irq context run in kthread context
again. Could you show me how you measured the performance of the kthread
approach versus the raw-IPI approach?
we can do a million kthread context switches per CPU per second, so
kthread context-switch cost cannot be a true performance limit, unless
you micro-benchmarked this.
Ingo
next prev parent reply other threads:[~2008-03-27 10:08 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-19 11:56 [PATCH 0/5] Generic smp_call_function(), improvements, and smp_call_function_single() Jens Axboe
2008-03-19 11:56 ` [PATCH 1/5] Add generic helpers for arch IPI function calls Jens Axboe
2008-03-19 11:56 ` [PATCH 2/5] x86: convert to generic helpers for " Jens Axboe
2008-03-19 11:56 ` [PATCH 3/5] x86-64: " Jens Axboe
2008-03-19 11:56 ` [PATCH 4/5] powerpc: " Jens Axboe
2008-03-19 11:56 ` [PATCH 5/5] ia64: " Jens Axboe
2008-03-21 9:53 ` [PATCH 0/5] Generic smp_call_function(), improvements, and smp_call_function_single() Ingo Molnar
2008-03-21 13:15 ` Jens Axboe
2008-03-25 8:00 ` Nick Piggin
2008-03-27 10:08 ` Ingo Molnar [this message]
2008-03-27 10:37 ` Jens Axboe
2008-03-27 10:43 ` Ingo Molnar
2008-03-27 12:02 ` Jens Axboe
2008-03-27 12:32 ` Ingo Molnar
2008-03-27 12:35 ` Jens Axboe
2008-03-21 18:22 ` Luck, Tony
2008-03-21 18:31 ` Jens Axboe
2008-03-21 18:56 ` Luck, Tony
2008-03-22 12:29 ` Jens Axboe
2008-03-24 16:45 ` Luck, Tony
2008-03-24 20:28 ` Luck, Tony
2008-03-25 8:12 ` Jens Axboe
2008-03-25 16:48 ` Luck, Tony
2008-03-25 18:00 ` Jens Axboe
2008-03-21 20:04 ` Luck, Tony
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