Messages in this thread | | | Date | Tue, 28 Jun 2022 11:39:38 +0800 | Subject | Re: [PATCH v4 1/7] sched/fair: default to false in test_idle_cores | From | Abel Wu <> |
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Hi Josh, thanks for your comments!
On 6/28/22 6:53 AM, Josh Don Wrote: > On Sun, Jun 19, 2022 at 5:05 AM Abel Wu <wuyun.abel@bytedance.com> wrote: >> >> It's uncertain whether idle cores exist or not if shared sched-domains >> are not ready, so returning "no idle cores" usually makes sense. >> >> While __update_idle_core() is an exception, it checks status of this >> core and set to shared sched-domain if necessary. So the whole logic >> depends on the existence of shared domain, and can bail out early if >> it isn't available. Modern compilers seems capable of handling such >> cases, so remove the tricky self-defined default return value. > > I don't think the compiler will be able to bail out of the smt > iteration early, since it'll have to do another rcu dereference for > the sd_llc in set(). But I also don't think this case needs > optimization, since it should be transient while the domain isn't > ready. > > Reviewed-by: Josh Don <joshdon@google.com>
Obviously I failed to comprehend the difference between the changed assembly code, my bad..
Thanks, Abel
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