| From | Linus Torvalds <> | Date | Fri, 15 Sep 2023 17:31:43 -0700 | Subject | Re: [PATCH 00/17] Add folio_end_read |
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On Fri, 15 Sept 2023 at 11:37, Matthew Wilcox (Oracle) <willy@infradead.org> wrote: > > I don't have any performance numbers; I'm hoping Nick might provide some > since PPC seems particularly unhappy with write-after-write hazards.
I suspect you can't see the extra atomic in the IO paths.
The existing trick with bit #7 is because we do a lot of page_lock/unlock pairs even when there is no actual IO. So it's worth it because page_unlock() really traditionally shows up quite a bit. But once you actually do IO, I think the effect is not measurable.
That said, the series doesn't look *wrong*, although I did note a few things that just made me go "that looks very strange to me" in there.
Linus
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