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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pXaAb-002A0I-Vi; Thu, 02 Mar 2023 04:03:54 +0000 Date: Thu, 2 Mar 2023 04:03:53 +0000 From: Matthew Wilcox To: Pasha Tatashin Cc: Gao Xiang , lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-nvme@lists.infradead.org, bpf@vger.kernel.org Subject: Re: [LSF/MM/BPF TOPIC] State Of The Page Message-ID: References: <8448beac-a119-330d-a2af-fc3531bdb930@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 6923580004 X-Stat-Signature: 8ijoy9n85i1fsoyyfz9hef871sniuyik X-Rspam-User: X-HE-Tag: 1677729847-347878 X-HE-Meta: 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 wfKSoAtu s6JfAkLZI0VSeqAG4TXLqs3JORTrl6STTNndzrSjiKUaCcmcnyhciWT9urKeOIaBgblBTlLU6917IDrnMgFlm8aFLopyxRegoouzuwhzDqhN5e8yTSiKFaM8ABf1WXakJTf7QzawQC84dvolMovDtBFpAhmM4oTEgFLE6ZIHO5dWcR6mbGiG1bD5kIJjMFNzY+7ojJenGvs3XlFqT2FDfnTkJhw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.001412, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 01, 2023 at 10:50:24PM -0500, Pasha Tatashin wrote: > On Tue, Feb 21, 2023 at 2:58 PM Matthew Wilcox wrote: > > My goal for 2023 is to get to a point where we (a) have struct page > > reduced to: > > > > struct page { > > unsigned long flags; > > struct list_head lru; > > struct address_space *mapping; > > pgoff_t index; > > unsigned long private; > > atomic_t _mapcount; > > atomic_t _refcount; > > unsigned long memcg_data; > > #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS > > int _last_cpupid; > > #endif > > }; > > This looks clean, but it is still 64-bytes. I wonder if we could > potentially reduce it down to 56 bytes by removing memcg_data. We need struct page to be 16-byte aligned to make slab work. We also need it to divide PAGE_SIZE evenly to make CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP work. I don't think it's worth nibbling around the edges like this anyway; convert everything from page to folio and then we can do the big bang conversion where struct page shrinks from 64 bytes to 8.