Commit r345200 (new ARC reclamation threads) looks suspicious to me - second potential problem
slw at zxy.spb.ru
Wed May 22 16:19:48 UTC 2019
On Wed, May 22, 2019 at 12:07:29PM -0400, Alexander Motin wrote:
> On 22.05.2019 11:50, Lev Serebryakov wrote:
> > On 22.05.2019 18:19, Alexander Motin wrote:
> >>>> But looks like `arc_kmem_reap_soon()` is synchronous on FreeBSD! So,
> >>>> this `delay()` looks very wrong. Am I right?
> >> Why is it wrong?
> > One second pause after synchronous operation to wait it completion?
> No. To rate-throttle them. This gives UMA a second to get back into
> minimally steady state after we ripped all caches from it. As I have
> told, we do not want to drain caches constantly in a tight loop, we want
> more or less steady state.
And also (posible) additionaly delay arc_get_data_impl().
This is incorrectly throttling implementation.
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