Messages in this thread | | | Date | Fri, 29 Oct 2021 09:42:19 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH 1/2] sched/fair: Couple wakee flips with heavy wakers |
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On Fri, Oct 29, 2021 at 12:19:48AM +0800, Tao Zhou wrote: > Hi Mel, > > On Thu, Oct 28, 2021 at 10:48:33AM +0100, Mel Gorman wrote: > > > @@ -5865,6 +5865,14 @@ static void record_wakee(struct task_struct *p) > > } > > > > if (current->last_wakee != p) { > > + int min = __this_cpu_read(sd_llc_size) << 1; > > + /* > > + * Couple the wakee flips to the waker for the case where it > > + * doesn't accrue flips, taking care to not push the wakee > > + * high enough that the wake_wide() heuristic fails. > > + */ > > + if (current->wakee_flips > p->wakee_flips * min) > > + p->wakee_flips++; > > current->last_wakee = p; > > current->wakee_flips++; > > } > > @@ -5895,7 +5903,7 @@ static int wake_wide(struct task_struct *p) > > > > if (master < slave) > > swap(master, slave); > > - if (slave < factor || master < slave * factor) > > + if ((slave < factor && master < (factor>>1)*factor) || master < slave * factor) > > So, the check like this include the above range: > > if ((slave < factor && master < slave * factor) || > master < slave * factor) > > That "factor>>1" filter some. > > If "slave < factor" is true and "master < (factor>>1)*factor" is false, > then we check "master < slave * factor".(This is one path added by the > check "&& master < (factor>>1)*factor"). > In the latter check "slave < factor" must be true, the result of this > check depend on slave in the range [factor, factor>>1] if there is possibility > that "master < slave * factor". If slave in [factor>>1, 0], the check of > "master < slave * factor" is absolutly false and this can be filtered if > we use a variable to load the result of master < (factor>>1)*factor. > > My random random inputs and continue confusing to move on. >
I'm not sure what point you're trying to make.
-- Mel Gorman SUSE Labs
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