Hi Lv, On Mon, Jul 03, 2017 at 01:15:26PM +0800, Zheng, Lv wrote: > Hi, Rafael > > > From: Rafael J. Wysocki [mailto:rjw@xxxxxxxxxxxxx] > > Subject: Re: [PATCH 3/3] ACPI: EC: Change EC noirq tuning to be an optional behavior > > > > On Wednesday, June 14, 2017 01:59:24 PM Lv Zheng wrote: > > > According to the bug report, though the busy polling mode can make noirq > > > stages executed faster, it causes abnormal fan blowing in noirq stages. > > > > > > This patch prepares an option so that the automatic busy polling mode > > > switching for noirq stages can be enabled by who wants to tune it, not all > > > users. > > > Noticed that the new global option cannot be changed during noirq stages. > > > There is no need to lock its value changes to sync with polling mode > > > settings switches. > > > > > > For reporters and testers in the thread, as there are too many reporters > > > on the bug link, this patch only picks names from most active commenters. > > > Sorry for the neglet. > > > > > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=191181 > > > Reported-by: Tatsuyuki Ishi <ishitatsuyuki@xxxxxxxxx> > > > Reported-by: Claudio Sacerdoti Coen <claudio.sacerdoticoen@xxxxxxxx> > > > Tested-by: Nicolo' <nicolopiazzalunga@xxxxxxxxx> > > > Reported-by: Jens Axboe <axboe@xxxxxxxxx> > > > Tested-by: Gjorgji Jankovski <j.gjorgji@xxxxxxxxx> > > > Tested-by: Damjan Georgievski <gdamjan@xxxxxxxxx> > > > Tested-by: Fernando Chaves <nanochaves@xxxxxxxxx> > > > Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx> > > > > First of all, this seems to be a fix for commit c3a696b6e8f8 (ACPI / EC: Use busy polling > > mode when GPE is not enabled), so there should be a Fixes: tag pointing to that > > one. > > > > Moreover, if that is just a performance optimization and not a matter of correctness, > > why don't we simply drop acpi_ec_enter/leave_noirq() entirely? > > > > What is going to break if we do that? > > Let me Cc Yu for justification. > I just added busy poll support for suspend/boot according to the root cause reported by him. > He should know the end user requirements better than me. > I remembered the original issue was reported against the slowness during suspend/resume due to the ec is running with GPE disabled, and falls into schedule_timeout() loop. If the busy polling mode is controlled by the boot options rather than acpi_ec_enter/leave_noirq(), then user should be noticed of the result that the cpu usage might be always higer if they enable the busy polling mode. Thanks, Yu > Thanks and best regards > Lv -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
