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Tue, 3 Dec 2024 10:23:53 -0800 (PST) Date: Tue, 3 Dec 2024 10:23:53 -0800 (PST) From: "Christoph Lameter (Ampere)" To: Jens Axboe cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, hannes@cmpxchg.org, clm@meta.com, linux-kernel@vger.kernel.org, willy@infradead.org, kirill@shutemov.name, bfoster@redhat.com Subject: Re: [PATCHSET v6 0/12] Uncached buffered IO In-Reply-To: <20241203153232.92224-2-axboe@kernel.dk> Message-ID: References: <20241203153232.92224-2-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: E4AC78001B X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: t4xwqgn67xgxwzyy3d1sw4ik68gzpsqj X-HE-Tag: 1733250208-254714 X-HE-Meta: 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 ak7iM3D4 FhsYeOW2vRFYxirdfRoBasPtqCRReeZgnBYeFAQj9osEXyFT+mHJ+QwxdlawVB9IdmRYi+MTbC+WrmMXjT2XG34Dp/3WGMQvfhRB+v3V/T0pJV3OViFHAaxNg6Ze0Hkkq07DhrUugYCALuWi6ybxI0ZHLqVckLOMeXRVuJMfRW1cj5u1/Ef3FneaMLcAispUW1JWoEQKCnzGiXU0= 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 Tue, 3 Dec 2024, Jens Axboe wrote: > > So here's a new approach to the same concent, but using the page cache > as synchronization. That makes RWF_UNCACHED less special, in that it's > just page cache IO, except it prunes the ranges once IO is completed. Great idea and someting that is really important these days. However, one nit that I have is the use of the term "uncached" for a folio/page. An uncached "page frame" refers to a page frame that requires accesses not going through the cpu cache. I.e. device mappings. This is an established mm/cpu term as far as I can tell. So maybe be a bit more specific about which cache this is? PAGE_CACHE_UNCACHED? or use a different term. It is cached after all but only for a brief period. So this may be a "TEMPORAL_PAGE" or so? (Similar to the x86 "non-temporal" stores).