From: Frederic Weisbecker <fweisbec@gmail.com> To: Stephen Boyd <sboyd@codeaurora.org> Cc: Kevin Hilman <khilman@linaro.org>, Russell King <linux@arm.linux.org.uk>, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs Date: Tue, 29 Oct 2013 09:25:48 +0100 [thread overview] Message-ID: <20131029082546.GA17514@localhost.localdomain> (raw) In-Reply-To: <20131029060058.GD21983@codeaurora.org> On Mon, Oct 28, 2013 at 11:00:58PM -0700, Stephen Boyd wrote: > On 10/28, Kevin Hilman wrote: > > Stephen Boyd <sboyd@codeaurora.org> writes: > > > > > This will allow the scheduler tick to be restarted if we're in > > > full NOHZ mode. > > > > > > Cc: Kevin Hilman <khilman@linaro.org> > > > Cc: Frederic Weisbecker <fweisbec@gmail.com> > > > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> > > > > Minor nit, but I'd prefer a more verbose changelog (I forget things > > quickly and like to rely on changelogs for my memory.) Probably worth > > adding something like: "By default, irq_work is tied to the tick > > processing (update_process_times()) but in full NOHZ mode, no tick means > > no IRQ work. In order for IRQ work to be done in full NOHZ mode, a > > self-IPI is used to process IRQ work." > > > > Other than the changelog nit, patch looks good, feel free to add > > > > Reviewed-by: Kevin Hilman <khilman@linaro.org> > > > > If Russell is OK with this, it can go to his patch system. > > > > Fair enough. This is what I came up with. I'll send it off to the > patch tracker in about 12 hours if nobody else has anymore > comments. > > ----8<----- > ARM: Support arch_irq_work_raise() via self IPIs > > By default, IRQ work is run from the tick interrupt (see > irq_work_run() in update_process_times()). When we're in full > NOHZ mode, restarting the tick requires the use of IRQ work and > if the only place we run IRQ work is in the tick interrupt we > have an unbreakable cycle. Implement arch_irq_work_raise() via > self IPIs to break this cycle and get the tick started again. > Note that we implement this via IPIs which are only available on > SMP builds. This shouldn't be a problem because full NOHZ is only > supported on SMP builds anyway. Nice description! Thanks! > > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> > Reviewed-by: Kevin Hilman <khilman@linaro.org> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > hosted by The Linux Foundation
WARNING: multiple messages have this Message-ID (diff)
From: fweisbec@gmail.com (Frederic Weisbecker) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs Date: Tue, 29 Oct 2013 09:25:48 +0100 [thread overview] Message-ID: <20131029082546.GA17514@localhost.localdomain> (raw) In-Reply-To: <20131029060058.GD21983@codeaurora.org> On Mon, Oct 28, 2013 at 11:00:58PM -0700, Stephen Boyd wrote: > On 10/28, Kevin Hilman wrote: > > Stephen Boyd <sboyd@codeaurora.org> writes: > > > > > This will allow the scheduler tick to be restarted if we're in > > > full NOHZ mode. > > > > > > Cc: Kevin Hilman <khilman@linaro.org> > > > Cc: Frederic Weisbecker <fweisbec@gmail.com> > > > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> > > > > Minor nit, but I'd prefer a more verbose changelog (I forget things > > quickly and like to rely on changelogs for my memory.) Probably worth > > adding something like: "By default, irq_work is tied to the tick > > processing (update_process_times()) but in full NOHZ mode, no tick means > > no IRQ work. In order for IRQ work to be done in full NOHZ mode, a > > self-IPI is used to process IRQ work." > > > > Other than the changelog nit, patch looks good, feel free to add > > > > Reviewed-by: Kevin Hilman <khilman@linaro.org> > > > > If Russell is OK with this, it can go to his patch system. > > > > Fair enough. This is what I came up with. I'll send it off to the > patch tracker in about 12 hours if nobody else has anymore > comments. > > ----8<----- > ARM: Support arch_irq_work_raise() via self IPIs > > By default, IRQ work is run from the tick interrupt (see > irq_work_run() in update_process_times()). When we're in full > NOHZ mode, restarting the tick requires the use of IRQ work and > if the only place we run IRQ work is in the tick interrupt we > have an unbreakable cycle. Implement arch_irq_work_raise() via > self IPIs to break this cycle and get the tick started again. > Note that we implement this via IPIs which are only available on > SMP builds. This shouldn't be a problem because full NOHZ is only > supported on SMP builds anyway. Nice description! Thanks! > > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> > Reviewed-by: Kevin Hilman <khilman@linaro.org> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > hosted by The Linux Foundation
next prev parent reply other threads:[~2013-10-29 8:25 UTC|newest] Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-10-03 13:58 [tip:timers/core] ARM: Kconfig: allow full nohz CPU accounting tip-bot for Kevin Hilman 2013-10-16 12:14 ` Frederic Weisbecker 2013-10-16 12:14 ` Frederic Weisbecker 2013-10-18 16:37 ` Stephen Boyd 2013-10-18 16:37 ` Stephen Boyd 2013-10-25 9:38 ` Frederic Weisbecker 2013-10-25 9:38 ` Frederic Weisbecker 2013-10-28 1:32 ` Kevin Hilman 2013-10-28 1:32 ` Kevin Hilman 2013-10-28 16:18 ` Stephen Boyd 2013-10-28 16:18 ` Stephen Boyd 2013-10-28 18:25 ` [PATCH] ARM: Support arch_irq_work_raise() via self IPIs Stephen Boyd 2013-10-28 18:25 ` Stephen Boyd 2013-10-29 1:58 ` Kevin Hilman 2013-10-29 1:58 ` Kevin Hilman 2013-10-29 6:00 ` Stephen Boyd 2013-10-29 6:00 ` Stephen Boyd 2013-10-29 8:25 ` Frederic Weisbecker [this message] 2013-10-29 8:25 ` Frederic Weisbecker 2013-10-29 18:55 ` Kevin Hilman 2013-10-29 18:55 ` Kevin Hilman 2013-11-08 20:06 ` Olof Johansson 2013-11-08 20:06 ` Olof Johansson 2013-11-08 20:45 ` Olof Johansson 2013-11-08 20:45 ` Olof Johansson 2013-11-08 21:53 ` Stephen Boyd 2013-11-08 21:53 ` Stephen Boyd 2013-11-08 23:35 ` Olof Johansson 2013-11-08 23:35 ` Olof Johansson 2013-11-08 23:39 ` Stephen Boyd 2013-11-08 23:39 ` Stephen Boyd 2013-11-09 0:01 ` Russell King - ARM Linux 2013-11-09 0:01 ` Russell King - ARM Linux 2013-11-09 0:07 ` Olof Johansson 2013-11-09 0:07 ` Olof Johansson
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