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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1r0i8v-0016aZ-7p; Wed, 08 Nov 2023 12:58:49 +0000 Date: Wed, 8 Nov 2023 12:58:49 +0000 From: Matthew Wilcox To: Ankur Arora Cc: Yosry Ahmed , Vlastimil Babka , Sergey Senozhatsky , linux-kernel@vger.kernel.org, tglx@linutronix.de, peterz@infradead.org, torvalds@linux-foundation.org, paulmck@kernel.org, linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, mgorman@suse.de, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, jgross@suse.com, andrew.cooper3@citrix.com, mingo@kernel.org, bristot@kernel.org, mathieu.desnoyers@efficios.com, geert@linux-m68k.org, glaubitz@physik.fu-berlin.de, anton.ivanov@cambridgegreys.com, mattst88@gmail.com, krypton@ulrich-teichert.org, rostedt@goodmis.org, David.Laight@aculab.com, richard@nod.at, mjguzik@gmail.com, SeongJae Park , Mike Kravetz , Muchun Song , Andrey Ryabinin , Marco Elver , Catalin Marinas , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Naoya Horiguchi , Miaohe Lin , David Hildenbrand , Oscar Salvador , Mike Rapoport , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Dennis Zhou , Tejun Heo , Christoph Lameter , Hugh Dickins , Pekka Enberg , David Rientjes , Joonsoo Kim , Vitaly Wool , Minchan Kim , Seth Jennings , Dan Streetman Subject: Re: [RFC PATCH 68/86] treewide: mm: remove cond_resched() Message-ID: References: <20231107215742.363031-1-ankur.a.arora@oracle.com> <20231107230822.371443-1-ankur.a.arora@oracle.com> <20231107230822.371443-12-ankur.a.arora@oracle.com> <20231108012823.GD11577@google.com> <7155f21f-a7e5-cc36-89e5-c1ce257b9420@suse.cz> <87sf5gocas.fsf@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87sf5gocas.fsf@oracle.com> X-Rspamd-Queue-Id: 1D530A000F X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 1j7rcfqurx83yn3a5q3ux9n9j18td14c X-HE-Tag: 1699448354-320543 X-HE-Meta: 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 jBz64vym UXzTheOZnF67/kfED6RdrJfj1vV5tU2EBF2YmzWtrzrrPNNm4sIfS5Ku29d+hyWBbd+FKRnyZYGnZHwg73S1wAWysmw8qOk16m4GwJUPlcUyd7OnSxKq7r0NGaITz0sjnWUydAW+u7Ym3h99y+nRhrFNjcVaIjUTUzo1XG3r//u1JMTI3U/XlDiLCKa3x/MoyrxXCSgk3q04gzzUfs3cjWhoFO1SGWjJgZGt0heW9i7IL3TwYkaCiDioSJfkZ16dyns0Mo5iQtoGR/vz53ulcbU4ohw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Nov 08, 2023 at 12:54:19AM -0800, Ankur Arora wrote: > Yosry Ahmed writes: > > On Tue, Nov 7, 2023 at 11:49 PM Vlastimil Babka wrote: > >> On 11/8/23 02:28, Sergey Senozhatsky wrote: > >> > I'd personally prefer to have a comment explaining why we do that > >> > spin_unlock/spin_lock sequence, which may look confusing to people. > >> > >> Wonder if it would make sense to have a lock operation that does the > >> unlock/lock as a self-documenting thing, and maybe could also be optimized > >> to first check if there's a actually a need for it (because TIF_NEED_RESCHED > >> or lock is contended). > > > > +1, I was going to suggest this as well. It can be extended to other > > locking types that disable preemption as well like RCU. Something like > > spin_lock_relax() or something. > > Good point. We actually do have exactly that: cond_resched_lock(). (And > similar RW lock variants.) That's a shame; I was going to suggest calling it spin_cycle() ...