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imf22.hostedemail.com; dkim=none; spf=pass (imf22.hostedemail.com: domain of dev.jain@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=dev.jain@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1746532449; a=rsa-sha256; cv=none; b=epdvxpkOpwqt8NN2OMLolb4hIo7/8xYtdzFY3LRsjrcBcBieq1U5DFxvOphjJw1ZXWeiDY z8IwVQqpzZqWitnHTGrr3QqBjiu6WBpgCzAcKNCrdGRzWimjplZ14mFBt7YGxTRbPkPk0t 5D36GOOjlQetZMB9FHcakyOy27ktjVM= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6D31D113E; Tue, 6 May 2025 04:53:58 -0700 (PDT) Received: from [10.163.80.199] (unknown [10.163.80.199]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 559E43F58B; Tue, 6 May 2025 04:53:58 -0700 (PDT) Message-ID: <81fbf59b-7930-4ee5-94a8-3756a372c4e6@arm.com> Date: Tue, 6 May 2025 17:23:51 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/3] Optimize mremap() by PTE-batching To: Lorenzo Stoakes Cc: Anshuman Khandual , akpm@linux-foundation.org, Liam.Howlett@oracle.com, vbabka@suse.cz, jannh@google.com, pfalcato@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@redhat.com, peterx@redhat.com, ryan.roberts@arm.com, mingo@kernel.org, libang.li@antgroup.com, maobibo@loongson.cn, zhengqi.arch@bytedance.com, baohua@kernel.org, willy@infradead.org, ioworker0@gmail.com, yang@os.amperecomputing.com References: <20250506050056.59250-1-dev.jain@arm.com> <4210a878-7dce-40c2-bd0b-0c2e39cdd80e@lucifer.local> Content-Language: en-US From: Dev Jain In-Reply-To: <4210a878-7dce-40c2-bd0b-0c2e39cdd80e@lucifer.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: a9r8dkhiet3d1hxt1npj79hj3b9ufro8 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: EFBB7C000E X-Rspam-User: X-HE-Tag: 1746532448-359872 X-HE-Meta: U2FsdGVkX1/dQNQUb2/oEI3XNRwuFxeZd/EV3oQJioCd/QTEnIzhYL/bq6lx75wun6Pd0dc6KRcX8dO2yOgK2YgLxpIUtIJyDh9VuSuVW235X1iqBOw8Vf4v4PnzTTt0cMekR7puZSmyhAo+w9hDJueyanqZtnNfeQ8gHtLg3JsqZ+GdJy/826rsu6WxmBCKLHLGQ1CyVxT6infeguyOYxJvn6NqdjNP9aciUQj2Yzv39bWJJyaBS4d+vCjWyb0RFkaUwaT2hwGuXfSool+xN1Em2/7GXsiveIw0NU4FPTi0jpXoqEnBW7qVlP+bCetchAxXNhrtbFiLisWtE7BKVGQtNH1FpC84BpVhzcVPljynV0NAm6dyZ1eLBoxIJBXZp/V9KCegd0wKCRe4JarW7/UvTwRauYCvdL4A9p4yIluhP85vrcVbNUhgTiL5B6EdA1J72qxA0/OBkfKd37XMt8vqxfm89HqexG4wnjxfksgrCpjs41/KbVhLcoW7Fi2GksZuXU7kSHp3Jm5PlBUW2sO97ONJSdjf6FiJQfDzGI+Q6s0PZcyWertuMk1Y6SmtQR+xfBsQzNshfIIRZUL0GgeumPggdKb/EZMs+tX31EJOeK/RkCNxbFZlewiOyTlmSzmiFx0RG2v2jwzO9QAlOI/Jy0QpBoCNWi1DzYXodTg1o6gVTfNXaG8owEdeJIV2TM3MVu7D5UNqVVSSh1elx3h5epB4I/ZrQSnWa07LV6X94zT7sjShZyCHUN0IJixT+H+BwKNmknnNAjESUUxnhrS0mY+UMVhyGxiNcvahs76JwKRsIzR4j+Yy6O/Ig+ddHEIDgDbAG74Iwik8igIiTsIpkpcBt8Ug 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 06/05/25 4:14 pm, Lorenzo Stoakes wrote: > On Tue, May 06, 2025 at 03:52:39PM +0530, Dev Jain wrote: >> >> >> On 06/05/25 2:46 pm, Anshuman Khandual wrote: >>> On 5/6/25 10:30, Dev Jain wrote: >>>> Use PTE batching to optimize mremap(). >>>> >>>> Mapping 512K of memory, memsetting it, remapping it to src + 512K, and >>>> munmapping it 10,000 times, the average execution time reduces from 1.9 to >>>> 1.2 seconds, giving a 37% performance optimization. (Apple M3) >>> >>> That's impressive improvement. But could you please re-organize the test >>> description into a pseudo code format or better provide the test program >>> itself (which should be compact anyways) just to be more clear about the >>> scenario where this helps. >> >> Sure. > > I echo Ashuman's comment, definitely would like to see that. > > And wrt to perf improvement, whether it's a microbenchmark or not, that's a > great result so well done :) I echo this also! > > However, it'd be good to see some more detail here also, you're kind of missing > out - everything - about why this improvement happens - what the intent of the > series is, anything about large folios, under what circumstances you'll see an > improvement, etc. etc. > > While this might duplicate comments you've made elsewhere, it's mandatory for a > series, and Andrew is unlikely to take this without it. > > In mm we place the contents of the cover letter in the first commit in the > series, so it gets stored for posterity also! > > Cheers, Lorenzo Thanks for your feedback. I'll make the required changes. > >> >>> >>>> >>>> Dev Jain (3): >>>> mm: Call pointers to ptes as ptep >>>> mm: Add generic helper to hint a large folio >>>> mm: Optimize mremap() by PTE batching >>>> >>>> include/linux/pgtable.h | 16 +++++++++++++++ >>>> mm/mremap.c | 44 +++++++++++++++++++++++++++-------------- >>>> 2 files changed, 45 insertions(+), 15 deletions(-) >>>> >>