Messages in this thread | | | Subject | Re: [PATCH] mm: move more expensive part of XA setup out of mapping check | From | Jens Axboe <> | Date | Tue, 26 Oct 2021 12:11:18 -0600 |
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On 10/26/21 12:08 PM, Matthew Wilcox wrote: > On Tue, Oct 26, 2021 at 10:01:20AM -0600, Jens Axboe wrote: >> The fast path here is not needing any writeback, yet we spend time setting >> up the xarray lookup data upfront. Move the part that actually needs to >> iterate the address space mapping into a separate helper, saving ~30% of >> the time here. > > No objection to this patch, but it did remind me that I never saw an answer to > https://lore.kernel.org/all/CAHk-=wg_-EwefQ_3Osz4iJxTrTk3tfrV53Z7-jaGg=tm9i5TXg@mail.gmail.com/ > (and nor did lore)
Totally missed that, and yes there could be cases where that lookup is going to be way too slow. I'll take a look.
-- Jens Axboe
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