On 2017.04.24 07:25 Doug wrote: > On 2017.04.23 18:23 Srinivas Pandruvada wrote: >> On Mon, 2017-04-24 at 02:59 +0200, Rafael J. Wysocki wrote: >>> On Sun, Apr 23, 2017 at 5:31 PM, Doug Smythies <dsmyth...@telus.net> wrote: > >>>> It looks like the cost is mostly related to moving the load from >>>> one CPU to >>>> another and waiting for the new one to ramp up then. >> Last time when we analyzed Mel's result last year this was the >> conclusion. The problem was more apparent on systems with per core P- >> state. > > ?? I have never seen this particular use case before. > Unless I have looked the wrong thing, Mel's issue last year was a > different use case. > > ...[cut]... > >>>>> We can do one more trick I forgot about. Namely, if we are about >>>>> to increase >>>>> the P-state, we can jump to the average between the target and >>>>> the max >>>>> instead of just the target, like in the appended patch (on top of >>>>> linux-next). >>>>> >>>>> That will make the P-state selection really aggressive, so costly >>>>> energetically, >>>>> but it shoud small jumps of the average load above 0 to case big >>>>> jumps of >>>>> the target P-state. >>>> I'm already seeing the energy costs of some of this stuff. >>>> 3050.2 Seconds. >>> Is this with or without reducing the sampling interval? > > It was without reducing the sample interval. > > So, it was the branch you referred us to the other day: > > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next > > with your patch (now deleted from this thread) applied. > > > ...[cut]... > >>> Anyway, your results are somewhat counter-intuitive. > >>> Would it be possible to run this workload with the linux-next branch >>> and the schedutil governor and see if the patch at >>> https://patchwork.kernel.org/patch/9671829/ makes any difference? > > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next > Plus that patch is in progress.
3387.76 Seconds. Idle power 3.85 watts. Other potentially interesting information for 2 hour idle test: Driver called 21209 times. Maximum duration 2396 Seconds. Minimum duration 20 mSec. Histogram of target pstates: 16 8 17 3149 18 1436 19 1479 20 196 21 2 22 3087 23 375 24 22 25 4 26 2 27 3736 28 2177 29 13 30 0 31 0 32 2 33 0 34 1533 35 246 36 0 37 4 38 3738 Compared to kernel 4.11-rc7 (passive mode, schedutil governor) 3297.82 (re-stated from a previous e-mail) Idle power 3.81 watts Other potentially interesting information for 2 hour idle test: Driver called 1631 times. Maximum duration 2510 Seconds. Minimum duration 0.587 mSec. Histogram of target pstates (missing lines mean 0 occurrences): 16 813 24 2 38 816 ... Doug
