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Date: Mon, 10 Jan 2022 16:02:33 +0100 From: Peter Zijlstra <peterz@...radead.org> To: Christoph Hellwig <hch@...radead.org> Cc: Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net, Tim Murray <timmurray@...gle.com>, Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>, Waiman Long <longman@...hat.com>, Boqun Feng <boqun.feng@...il.com> Subject: Re: [PATCH] f2fs: move f2fs to use reader-unfair rwsems On Mon, Jan 10, 2022 at 12:05:26AM -0800, Christoph Hellwig wrote: > Adding the locking primitive maintainers to this patch adding open coded > locking primitives.. > > On Sat, Jan 08, 2022 at 08:46:17AM -0800, Jaegeuk Kim wrote: > > From: Tim Murray <timmurray@...gle.com> > > > > f2fs rw_semaphores work better if writers can starve readers, > > especially for the checkpoint thread, because writers are strictly > > more important than reader threads. This prevents significant priority > > inversion between low-priority readers that blocked while trying to > > acquire the read lock and a second acquisition of the write lock that > > might be blocking high priority work. *groan*... that's nowhere near enough Changelog to justify any of this. Because next is a whole series of patches making things even worse because lockdep no longers works as expected on this custom thing. Can we start by describing the actual problem?
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