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Fri, 26 Feb 2021 11:49:46 -0800 (PST) Received: from google.com ([2620:15c:183:200:bd06:d32d:458e:cd3a]) by smtp.gmail.com with ESMTPSA id w1sm4829876ilv.52.2021.02.26.11.49.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Feb 2021 11:49:45 -0800 (PST) Date: Fri, 26 Feb 2021 12:49:41 -0700 From: Yu Zhao To: Matthew Wilcox Cc: akpm@linux-foundation.org, alex.shi@linux.alibaba.com, vbabka@suse.cz, guro@fb.com, hannes@cmpxchg.org, hughd@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, vdavydov.dev@gmail.com Subject: Re: [PATCH v2 3/3] mm: use PF_ONLY_HEAD for PG_active and PG_unevictable Message-ID: References: <20210224084807.2179942-1-yuzhao@google.com> <20210226091718.2927291-1-yuzhao@google.com> <20210226091718.2927291-4-yuzhao@google.com> <20210226121314.GB2723601@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210226121314.GB2723601@casper.infradead.org> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 039A9C0007C1 X-Stat-Signature: dj4d8kkeg6jqitqifg31x5s6gsxaxzgw Received-SPF: none (google.com>: No applicable sender policy available) receiver=imf06; identity=mailfrom; envelope-from=""; helo=mail-il1-f169.google.com; client-ip=209.85.166.169 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614368988-779440 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: On Fri, Feb 26, 2021 at 12:13:14PM +0000, Matthew Wilcox wrote: > On Fri, Feb 26, 2021 at 02:17:18AM -0700, Yu Zhao wrote: > > All places but one test, set or clear PG_active and PG_unevictable on > > small or head pages. Use compound_head() explicitly for that singleton > > so the rest can rid of redundant compound_head(). > > How do you know it's only one place? I really wish you'd work with me > on folios. They make the compiler prove that it's not a tail page. I hasn't been following the effort closely, so I'm rereading the very first discussion "Are THPs the right model for the pagecache?" and then I need to rewatch the recorded Zoom meeting. As I said I'm on board with the idea, but I can't create a roadmap based on my current rough understanding, unless you prefer me to just randomly throw some reviewed-bys at your patches in the next few days. (Our long-term plan for folios is to support arbitrary anon page sizes because anon memory is more than 90% of total user memory on Android, Chrome OS and in our data centers.) That said, if you have something ready to test, we could do it for you in our runtime environments immediately.