Messages in this thread | | | Date | Tue, 29 Oct 2013 09:25:48 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs |
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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
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