Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [GIT PULL] sigqueue cache fix | Date | Wed, 07 Jul 2021 11:47:47 +0200 |
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Linus,
On Mon, Jun 28 2021 at 12:02, Linus Torvalds wrote: > And as the whole - and only - point of the sigqueue cache was a very > subtle performance and latency issue, I don't think we want to use > locks or atomics. It's why my revert commit suggests re-purposing the > "percpu_cmpxchg()" functionality: that would likely be a good model at > least for x86 and arm. > > But while we have "percpu_cmpxchg()", I don't think we currently don't > really have that kind of operation where it > > (a) works on a non-percpu variable (but we can force casts, I guess) > > (b) has "acquire" semantics > > We do have the *atomic* cmpxchg with acquire semantics, but atomics > are rather more expensive than we'd probably really want.
first of all, sorry for being non-responsive on this. I'll have a fresh look at this with your comments in mind and be more careful.
Thanks,
tglx
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