Messages in this thread | | | Date | Fri, 15 Sep 2023 17:43:20 +0200 | Subject | Re: [PATCH 0/6] shmem: high order folios support in write path | From | David Hildenbrand <> |
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On 15.09.23 17:40, Matthew Wilcox wrote: > On Fri, Sep 15, 2023 at 05:36:27PM +0200, David Hildenbrand wrote: >> On 15.09.23 17:34, Matthew Wilcox wrote: >>> No, it can't. This patchset triggers only on write, not on read or page >>> fault, and it's conservative, so it will only allocate folios which are >>> entirely covered by the write. IOW this is memory we must allocate in >>> order to satisfy the write; we're just allocating it in larger chunks >>> when we can. >> >> Oh, good! I was assuming you would eventually over-allocate on the write >> path. > > We might! But that would be a different patchset, and it would be > subject to its own discussion. > > Something else I've been wondering about is possibly reallocating the > pages on a write. This would apply to both normal files and shmem. > If you read in a file one byte at a time, then overwrite a big chunk of > it with a large single write, that seems like a good signal that maybe > we should manage that part of the file as a single large chunk instead > of individual pages. Maybe. > > Lots of things for people who are obsessed with performance to play > with ;-)
:) Absolutely. ... because if nobody will be consuming that written memory any time soon, it might also be the wrong place for a large/huge folio.
-- Cheers,
David / dhildenb
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