On 01/09/2019 12:44 PM, Matthew Wilcox wrote: > On Wed, Jan 09, 2019 at 12:23:44PM -0500, Waiman Long wrote: >> This v2 patch optimizes the way the IRQ counts are retrieved and computed >> and getting rid of the sysctl parameter altogether to achieve a performance >> gain that is close to the v1 patch. This is based on the idea that while >> many IRQs can be supported by a system, only a handful of them are actually >> being used in most cases. We can save a lot of time by focusing on those >> active IRQs only and ignore the rests. > So your reaction to being told "Make this the same as every other thing > we have to sum across all CPUs" is to make it _even more different_ and > special-cased? I'm done. NAK. The paragraph above may be a bit misleading. This v2 patch actually touches very little on percpu accounting aspect of the IRQ counts. See patches 2 and 3 for the relevant changes which is just a few line of new codes. Please review the individual patches before Nak'ing. I could theoretically generalize them into a new set of percpu counting helpers, but the idea behind it is quite different from the use cases of percpu counter. So it may not be a good idea of adding it to there. Cheers, Longman
