Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH 0/6] cpuidle: menu: Fixes, optimizations and cleanups | Date | Tue, 09 Oct 2018 12:42:38 +0200 |
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On Tuesday, October 9, 2018 12:26:48 AM CEST Rafael J. Wysocki wrote: > On Tue, Oct 9, 2018 at 12:14 AM Doug Smythies <dsmythies@telus.net> wrote: > > > > On 2018.10.08 00:51 Rafael J. Wysocki wrote: > > > On Mon, Oct 8, 2018 at 8:02 AM Doug Smythies <dsmythies@telus.net> wrote: > > >> > > >> On 2018.10.03 23:56 Rafael J. Wysocki wrote: > > >>> On Tue, Oct 2, 2018 at 11:51 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > [cut] > > > >> Test 2: pipe test 2 CPUs, one core. CPU test: > > >> > > >> The average loop times graph is here: > > >> http://fast.smythies.com/linux-pm/k419/k419-rjw-pipe-1core.png > > >> > > >> The power and idle statistics graphs are here: > > >> http://fast.smythies.com/linux-pm/k419/k419-rjw-pipe-1core.htm > > >> > > >> Conclusions: > > >> > > >> Better performance at the cost of more power with > > >> the patch set, but late August had both better performance > > >> and less power. > > >> > > >> Overall idle entries and exits are about the same, but way > > >> way more idle state 0 entries and exits with the patch set. > > > > > >Same as above (and expected too). > > > > I Disagree. The significant transfer of idle entries from > > idle state 1 with kernel 4.19-rc6 to idle state 0 with the > > additional 8 patch set is virtually entirely due to this patch: > > > > "[PATCH 2/6] cpuidle: menu: Compute first_idx when latency_req is known" > > OK > > > As far as I can determine from all of this data, in particular the > > histogram data below, it seems to me that it now is selecting > > idle state 0 whereas before it was selecting idle state 1 > > is the correct decision for those very short duration idle states > > (well, for my processor (older i7-2600K) at least). > > At least, that's a matter of consistency IMO. > > State 1 should not be selected if the final latency limit is below its > exit latency and that's what happens in that situation. > > > Note: I did test my above assertion with kernels compiled with only > > the first 2 and then 3 of the 8 patch set. > > I see.
While at it, could you test the appended patch (on top of the previous 8) for me please?
I think that this code can be simplified now.
--- drivers/cpuidle/governors/menu.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
Index: linux-pm/drivers/cpuidle/governors/menu.c =================================================================== --- linux-pm.orig/drivers/cpuidle/governors/menu.c +++ linux-pm/drivers/cpuidle/governors/menu.c @@ -371,12 +371,12 @@ static int menu_select(struct cpuidle_dr if (s->target_residency > predicted_us) { /* * Use a physical idle state, not busy polling, unless - * a timer is going to trigger really really soon. + * a timer is going to trigger soon enough. */ if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && - i == idx + 1 && latency_req > s->exit_latency && - data->next_timer_us > max_t(unsigned int, 20, - s->target_residency)) { + s->exit_latency <= latency_req && + s->target_residency <= data->next_timer_us) { + predicted_us = s->target_residency; idx = i; break; }
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