Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932803AbaFCPAU (ORCPT ); Tue, 3 Jun 2014 11:00:20 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:54963 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932762AbaFCPAS (ORCPT ); Tue, 3 Jun 2014 11:00:18 -0400 Date: Tue, 3 Jun 2014 17:00:08 +0200 From: Peter Zijlstra To: Frederic Weisbecker Cc: Ingo Molnar , LKML , Andrew Morton , Kevin Hilman , "Paul E. McKenney" , Thomas Gleixner , Viresh Kumar Subject: Re: [PATCH 3/5] irq_work: Implement remote queueing Message-ID: <20140603150008.GT30445@twins.programming.kicks-ass.net> References: <1401806420-31018-1-git-send-email-fweisbec@gmail.com> <1401806420-31018-4-git-send-email-fweisbec@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="X0hJ4E3r/0nQXmJY" Content-Disposition: inline In-Reply-To: <1401806420-31018-4-git-send-email-fweisbec@gmail.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --X0hJ4E3r/0nQXmJY Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jun 03, 2014 at 04:40:18PM +0200, Frederic Weisbecker wrote: > irq work currently only supports local callbacks. However its code > is mostly ready to run remote callbacks and we have some potential user. >=20 > The full nohz subsystem currently open codes its own remote irq work > on top of the scheduler ipi when it wants a CPU to reevaluate its next > tick. However this ad hoc solution bloats the scheduler IPI. >=20 > Lets just extend the irq work subsystem to support remote queuing on top > of the generic SMP IPI to handle this kind of user. This shouldn't add > noticeable overhead. >=20 > Suggested-by: Peter Zijlstra > Cc: Andrew Morton > Cc: Ingo Molnar > Cc: Kevin Hilman > Cc: Paul E. McKenney Acked-by: Peter Zijlstra > Cc: Thomas Gleixner > Cc: Viresh Kumar > Signed-off-by: Frederic Weisbecker > --- > include/linux/irq_work.h | 2 ++ > kernel/irq_work.c | 22 +++++++++++++++++++++- > kernel/smp.c | 4 ++++ > 3 files changed, 27 insertions(+), 1 deletion(-) > @@ -198,6 +199,9 @@ void generic_smp_call_function_single_interrupt(void) > csd->func(csd->info); > csd_unlock(csd); > } > + > + /* Handle irq works queued remotely by irq_work_queue_on() */ > + irq_work_run(); > } One could possibly extend that comment by stating that we explicitly run the irq_work bits after the function bits, because the function bits are typically synchronous and have people waiting on them, while not so for the irq_works. --X0hJ4E3r/0nQXmJY Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTjeL4AAoJEHZH4aRLwOS6DF0P/i2WrdV59D1b5uKMh/+U5mJt C0xpOYVJ0k9wzIzcAKkojCWjQcxGOvD0uutL2MUrBL7Jw5XB9Xt02ADzF/NnSL8N 6+NxxHgfQQTaN2eVtsEC17gEcO7bZH7ecyBepGV1Rvoue9k4NDGVXAsPaGnxth0t n3x2jZImhEXNmxqzR8d+ayNpTBR/or0T76i0g9BIg4/45RSu5v058uOF6L6UEraE 85ebPQM8sKBGnALSeZx/iSUjhPV/sIDUjuFN6tRxpb9otrwcduOPqPCf21PyPJK8 qnRudWDTnwmO9x2O2BAkjsFMNBmIPb06TeTOXGqUQ1VZnp7m6saHBGNCtbk502vz EF8XkK+rKVPw23AJ3qzBKBVK8QGBs5losq87v0nhzc91KPIqam7lnmiGLUuRbHUG dvyZWoZUb0z4/C1zsUbBrDSwu3Fo4HtEudPQfpz/ai0v/CW0Wczu5DlMqK3lZBjJ mmd44fAfpjWtwk/2kdJDbijCoxpazWfRKriS4+MXtMLrODaeRanvzqr4l/fgcQGw QRRrccEpRYDUyCzjlRC8sGhp1IvLHYbjQOFXr+43vupzcJebyuwgK3cPnulR1QIq yx7M9gFNUugWDXyLtol7kvNxaAVjWXRpSaJlDs7f6V9yNn8kukt3q5oLMZBuEntI q2R7eLGD3GloN1Xi1l8E =zsWV -----END PGP SIGNATURE----- --X0hJ4E3r/0nQXmJY-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/