From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Shi Subject: Re: [PATCH v2 6/8] mm/lru: remove rcu_read_lock to fix performance regression Date: Wed, 13 Nov 2019 10:40:58 +0800 Message-ID: References: <1573567588-47048-1-git-send-email-alex.shi@linux.alibaba.com> <1573567588-47048-7-git-send-email-alex.shi@linux.alibaba.com> <20191112143844.GB7934@bombadil.infradead.org> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20191112143844.GB7934@bombadil.infradead.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="iso-8859-1" To: Matthew Wilcox Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mgorman@techsingularity.net, tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com, Johannes Weiner , Roman Gushchin , Shakeel Butt , Chris Down , Thomas Gleixner =D4=DA 2019/11/12 =CF=C2=CE=E710:38, Matthew Wilcox =D0=B4=B5=C0: > On Tue, Nov 12, 2019 at 10:06:26PM +0800, Alex Shi wrote: >> Intel 0day report there are performance regression on this patchset. >> The detailed info points to rcu_read_lock + PROVE_LOCKING which causes >> queued_spin_lock_slowpath waiting too long time to get lock. >> Remove rcu_read_lock is safe here since we had a spinlock hold. > Argh. You have not sent these patches in a properly reviewable form! > I wasted all that time reviewing the earlier patch in this series only to > find out that you changed it here. FIX THE PATCH, don't send a fix-patch > on top of it! >=20 Hi Matthew, Very sorry for your time! The main reasons I use a separate patch since a, = Intel 0day asking me to credit their are founding, and I don't know how to = give a clearly/elegant explanation for a non-exist regression in a fixed pa= tch. b, this regression is kindly pretty tricky. Maybe it's better saying = thanks in version change log of cover-letter? Anyway, Thanks a lot for your review! Alex