From mboxrd@z Thu Jan 1 00:00:00 1970 From: kmcmarti@redhat.com (Kyle McMartin) Date: Sat, 10 Jan 2015 10:22:59 -0500 Subject: Linux 3.19-rc3 In-Reply-To: <54B09CA3.1060501@redhat.com> References: <54AE7D53.2020305@redhat.com> <20150109121348.GD12942@leverpostej> <54AFE53A.4020004@redhat.com> <20150109175702.GA27787@leverpostej> <54B01FF0.3020900@arm.com> <20150109194333.GA23028@arm.com> <54B09CA3.1060501@redhat.com> Message-ID: <20150110152259.GP18580@redacted.bos.redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sat, Jan 10, 2015 at 04:29:39AM +0100, Laszlo Ersek wrote: > I've bisected this issue to > Awesome, this was on my list of list of suspicious commits to check before my ARM64 box decided not to come back from reboot on Friday. :) Thanks for bisecting! cheers, --Kyle > > f045bbb9fa1bf6f507ad4de12d4e3471d8f672f1 is the first bad commit > > commit f045bbb9fa1bf6f507ad4de12d4e3471d8f672f1 > > Author: Linus Torvalds > > Date: Wed Dec 17 11:59:04 2014 -0800 > > > > mmu_gather: fix over-eager tlb_flush_mmu_free() calling > > > > Dave Hansen reports that commit fb7332a9fedf ("mmu_gather: move minimal > > range calculations into generic code") caused a performance problem: > > > > "tlb_finish_mmu() goes up about 9x in the profiles (~0.4%->3.6%) and > > tlb_flush_mmu_free() takes about 3.1% of CPU time with the patch > > applied, but does not show up at all on the commit before" > > > > and the reason is that Will moved the test for whether we need to flush > > from tlb_flush_mmu() into tlb_flush_mmu_tlbonly(). But that meant that > > tlb_flush_mmu_free() basically lost that check. > > > > Move it back into tlb_flush_mmu() where it belongs, so that it covers > > both tlb_flush_mmu_tlbonly() _and_ tlb_flush_mmu_free(). > > > > Reported-and-tested-by: Dave Hansen > > Acked-by: Will Deacon > > Signed-off-by: Linus Torvalds > >