Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 19 Aug 2020 09:22:13 +0200 | From | Christoph Hellwig <> | Subject | iter and normal ops on /dev/zero & co, was Re: remove the last set_fs() in common code, and remove it for x86 and powerpc |
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On Wed, Aug 19, 2020 at 09:16:59AM +0200, Christophe Leroy wrote: > I made a test with only the first patch of your series: That's definitely > the culprit. With only that patch applies, the duration is 6.64 seconds, > that's a 25% degradation.
For the record: the first patch is:
mem: remove duplicate ops for /dev/zero and /dev/null
So these micro-optimizations matter at least for some popular benchmarks. It would be easy to drop, but that means we either:
- can't support kernel_read/write on these files, which should not matter
or
- have to drop the check for both ops being present
Al, what do you think?
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