Messages in this thread | | | Date | Fri, 31 Mar 2023 17:21:48 +0100 | Subject | Re: [RFC 00/11] optimise registered buffer/file updates | From | Pavel Begunkov <> |
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On 3/31/23 14:35, Gabriel Krisman Bertazi wrote: > Pavel, > > Pavel Begunkov <asml.silence@gmail.com> writes: >> Updating registered files and buffers is a very slow operation, which >> makes it not feasible for workloads with medium update frequencies. >> Rework the underlying rsrc infra for greater performance and lesser >> memory footprint. >> >> The improvement is ~11x for a benchmark updating files in a loop >> (1040K -> 11468K updates / sec). > > Nice. That's a really impressive improvement. > > I've been adding io_uring test cases for automated performance > regression testing with mmtests (open source). I'd love to take a look > at this test case and adapt it to mmtests, so we can pick it up and run > it frequently. > > is it something you can share?
I'll post it later.
The test is quite stupid and with the patches less than 10% of CPU cycles go to the update machinery (against 90+ w/o), the rest is spend for syscalling, submitting update requests, etc., so it almost hits the limit.
Another test we can do is to measure latency b/w the point we asked a rsrc to be removed and when it actually got destroyed/freed, e.g. tags will help with that. It should've been improved nicely as well as it removes the RCU grace period and other bouncing.
-- Pavel Begunkov
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