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Tue, 3 Mar 2026 10:39:49 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id UTCrJ3W6pmmwGwAAD6G6ig (envelope-from ); Tue, 03 Mar 2026 10:39:49 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 5E5C8A0A1B; Tue, 3 Mar 2026 11:39:49 +0100 (CET) Date: Tue, 3 Mar 2026 11:39:49 +0100 From: Jan Kara To: Matthew Wilcox Cc: Jan Kara , Tal Zussman , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Jens Axboe , Alexander Viro , Christian Brauner , Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: [PATCH RFC v3 1/2] filemap: defer dropbehind invalidation from IRQ context Message-ID: References: <20260227-blk-dontcache-v3-0-cd309ccd5868@columbia.edu> <20260227-blk-dontcache-v3-1-cd309ccd5868@columbia.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Action: no action X-Rspamd-Queue-Id: 77802180012 X-Stat-Signature: 3wd7swt8rtoyw7dnuni4smcuxwdazs81 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1772534391-390751 X-HE-Meta: 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 uVFp0Wbo DN+g1QzCkSb1S9dj14NEH1CjZkr5iNj/EpExO08RkL6btDpYEGCKt6xKQyKA5ItHD2dscp+Bh5PncTMVS1mxa6i8D/YYnf9NVEm8sKKSg6eI3B7MrFcUl5zOneIT3SsQuYe8zM112OoNYzOS1m1iNivkKPhAbS2ZU53I5LHaWQmZPEpQMj1Ce3zCJsKTln8OU2TfbMigSCaZonztLQeZi9b0Ux47ANW0FZ4fOqiGF18NGLDaA/3NnaF4Xx1muGZ75lByNsocizKm0uoS7fYxKH2KokWUnTBHAR7DUw8M9tsWdDfFSDuWwSFhq/Xlwu+7xWLV7SQfiky+ihqnzCodA1EXqdeFr8oZFGx/Hh0eu8OLMw6KyRVJ6W/MtQkWcuRSjsI+PM4DpKojR3AH+hh5qkMrBmBbwPvB+tZIW78oO/Jn74Xw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon 02-03-26 17:37:23, Matthew Wilcox wrote: > On Mon, Mar 02, 2026 at 10:11:19AM +0100, Jan Kara wrote: > > Folio batches are relatively small (31 folios). With 4k folios it is very > > easy to overflow the batch with a single IO completion. Large folios will > > obviously make this less likely but I'm not sure reasonable working of > > dropbehind should be dependent on large folios... Not sure how to best > > address this though. We could use larger batches but that would mean using > > our own array of folios instead of folio_batch. > > That's why I think we should allow the bio to be tagged as > "finish the bio in workqueue context", > https://lore.kernel.org/linux-fsdevel/aaC3LUFa1Jz2ahk3@casper.infradead.org/ Yeah, what you suggested there makes sense to me. The workqueue would probably have to be a per-cpu one for performance reasons but otherwise I think it's worth a try. Honza -- Jan Kara SUSE Labs, CR