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Wed, 8 Nov 2023 07:49:18 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id VX3RJH49S2VuIwAAMHmgww (envelope-from ); Wed, 08 Nov 2023 07:49:18 +0000 Message-ID: <7155f21f-a7e5-cc36-89e5-c1ce257b9420@suse.cz> Date: Wed, 8 Nov 2023 08:49:18 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [RFC PATCH 68/86] treewide: mm: remove cond_resched() Content-Language: en-US To: Sergey Senozhatsky , Ankur Arora Cc: 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, willy@infradead.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 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> From: Vlastimil Babka In-Reply-To: <20231108012823.GD11577@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 19BAA80011 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: ndn4fg5be4ssum3zf7oz3stispu596gf X-HE-Tag: 1699429761-377320 X-HE-Meta: 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 zWQsECke XpUFHy/UT92l5Dur+so9wE3k9rKnZH1iUjaNxkVSovjZwqRZ3q7fWWnt+nlqCG4AZmTUJQPdloJwO/G77KuqteSoD7hbvHsyvtD510DOrDtjL1an2dJOSrvru+/KAWIin5+WBuIpy1oTsiKagEBaJM+/f1g0I3DaX7/etgkvzbKqUdwPCDP42bDA9WLZpgYaTbNb0WI493Aw15XF0dflfwNaZNnB9KkZW11TszPxKPHAJBd5sSgbON00Yn+p/XnAVRK/Avuu0sfOic+5B8HI/CvoUaW/s3n6TH91JrBxQ3AObWDqtTP2BDZgXB6Q6VYCbzT5W 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 11/8/23 02:28, Sergey Senozhatsky wrote: > On (23/11/07 15:08), Ankur Arora wrote: > [..] >> +++ b/mm/zsmalloc.c >> @@ -2029,7 +2029,6 @@ static unsigned long __zs_compact(struct zs_pool *pool, >> dst_zspage = NULL; >> >> spin_unlock(&pool->lock); >> - cond_resched(); >> spin_lock(&pool->lock); >> } >> } > > 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). > Maybe would make sense to put a nice comment in all similar cases. > For instance: > > rcu_read_unlock(); > - cond_resched(); > rcu_read_lock();