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Tue, 2 Apr 2024 09:41:58 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap2.dmz-prg2.suse.org with ESMTPSA id BuEkG+bSC2YIAgAAn2gu4w (envelope-from ); Tue, 02 Apr 2024 09:41:58 +0000 Message-ID: <69089796-9a3b-41a1-9b7c-18c773b96aa2@suse.cz> Date: Tue, 2 Apr 2024 11:41:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/4] mm/slub: simplify get_partial_node() Content-Language: en-US To: xiongwei.song@windriver.com, rientjes@google.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, chengming.zhou@linux.dev References: <20240331021926.2732572-1-xiongwei.song@windriver.com> <20240331021926.2732572-4-xiongwei.song@windriver.com> From: Vlastimil Babka In-Reply-To: <20240331021926.2732572-4-xiongwei.song@windriver.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: jycgx3ap8rqtrtwaq9ptcapoeez4dyiy X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 747972000C X-Rspam-User: X-HE-Tag: 1712050920-872732 X-HE-Meta: U2FsdGVkX18J+vzu91DXt9QoszUou5Jg1V92nyZMa3ExGz5qiwLCVXg25DkcG+jteKrPfhUB/2KThAf6BlXeF5b83qWG3/vTAHhshXqj1F76x+TjUXXED150AoNs7c87ijxqrpzms2wykFOt0gyCom0HjyPMtYZipNlU7V15hmzPvEF1EJj/s5LFVPia4+ZyAVOPNtO8Izz5Fre/VjJApzk3bJ5Is+HHFCaFVT7S9+xtBNahuB5B94K+7WODl6Og4MORHRh6IFABAnR1t5mJ6zqovteULJe4OvdKD7YF7MLG96BmaqvLE/utDsBmWaGClTHFABL5P0+VqNNbTWfCy/aNLOqmJUo/sXQ9BIcMlzHS4lxMjBcBdaZcyMdMObasc1mOwL/NuBXeNoe5hER1BvYHBzgxU8yt6PRsEl3buz/Yda0nW29rczkFsPmXug9aW5BIUDCNFHMLY096g71+EDjf0ovQsSNccMk7+F22G93sYlj2gLYm5et19mTRk3DOzpjsz8l6ytccxtBwscuF5ICb5NPdYH2DiNLVuMe6gfc/cfkNGncH+I4kf2Mqp+MdT7vFPjn7qCSh2Rvg6YvuM0R36Q3WrfRulE4tklWESan9xfQ36IUMM6O1SzByiVqelh4kaQXBfsQ2SFcex9c3ioa+Vd/PNgrARbWlbbY97IuNrEOnEqvYLsqssujB0VXDpG0TyvGXQbe48lwqfy+9rm4vFpOm5L8ni61QiWXfyrmslIYniWMXNqEQi6tByNlPYEL3V5/cqYzYTQwLKeO4sl07DFrEiR0apWv4qU/Q3q4wfnxeAKjUDmi0zPlrmiB4JejcDdUNk9Zkc5PIf4qL/7uhlEzHDz05AORmcM2uw/sICqrXsh8qYc9idCP1S3e+tuz/dM79XEO7CnGkPJJ5hMwL46PRUkOHP0T3/7/X/HZYpA9QrOCwVdb/noQgfHTENKjcBJ/ipGuvegFD31x npKGaGuP zDczuBwEFa80m2KL01m7hLZkydr/DVQL3HiiP07RPSKbgbxPP0HzvfRBIy7gpR0SX+g1nR+JrtFo8FRrQKLb/YUKmvE/+cjEipvn1OTtGN8G4Qbj8EW64zFqYI0au2U0JtAJq9BbcwITzai2iNbhsvYZsjmnz4SNCyktlRWsZJ50Uuh4bFoc+cAL8M/wshvT+CBbHFFhirhT1+unnWaR5YsyGKnNQlatwA1mn0tMABSOXIkZvCcdlXCDErQp6YcnyBY7OTSXQF4meVeqIwMfajYWBgdWPwEzb+iakU4fnARZHHwEkXNCdgu5re+2Vsyq39q+J53NVedxS16565IhsAVYb/ybJnUWG/Cmvi0hQsOIJqJiNTbptjEHErtX3+4eapiNE+k+i3EXcGpsMJwUHUYxbFiAuMOTyY+H1ISIxbHXRr1axWis0i+1kMQ== 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 3/31/24 4:19 AM, xiongwei.song@windriver.com wrote: > From: Xiongwei Song > > The break conditions can be more readable and simple. > > We can check if we need to fill cpu partial after getting the first > partial slab. If kmem_cache_has_cpu_partial() returns true, we fill > cpu partial from next iteration, or break up the loop. > > Then we can remove the preprocessor condition of > CONFIG_SLUB_CPU_PARTIAL. Use dummy slub_get_cpu_partial() to make > compiler silent. > > Signed-off-by: Xiongwei Song > --- > mm/slub.c | 22 ++++++++++++---------- > 1 file changed, 12 insertions(+), 10 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 590cc953895d..ec91c7435d4e 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2614,18 +2614,20 @@ static struct slab *get_partial_node(struct kmem_cache *s, > if (!partial) { > partial = slab; > stat(s, ALLOC_FROM_PARTIAL); > - } else { > - put_cpu_partial(s, slab, 0); > - stat(s, CPU_PARTIAL_NODE); > - partial_slabs++; > + > + /* Fill cpu partial if needed from next iteration, or break */ > + if (kmem_cache_has_cpu_partial(s)) That kinda puts back the check removed in patch 1, although only in the first iteration. Still not ideal. > + continue; > + else > + break; > } > -#ifdef CONFIG_SLUB_CPU_PARTIAL > - if (partial_slabs > s->cpu_partial_slabs / 2) > - break; > -#else > - break; > -#endif I'd suggest intead of the changes done in this patch, only change this part above to: if ((slub_get_cpu_partial(s) == 0) || (partial_slabs > slub_get_cpu_partial(s) / 2)) break; That gets rid of the #ifdef and also fixes a weird corner case that if we set cpu_partial_slabs to 0 from sysfs, we still allocate at least one here. It could be tempting to use >= instead of > to achieve the same effect but that would have unintended performance effects that would best be evaluated separately. > > + put_cpu_partial(s, slab, 0); > + stat(s, CPU_PARTIAL_NODE); > + partial_slabs++; > + > + if (partial_slabs > slub_get_cpu_partial(s) / 2) > + break; > } > spin_unlock_irqrestore(&n->list_lock, flags); > return partial;