On Mon, Feb 13, 2017 at 2:51 PM, Peter Zijlstra <[email protected]> wrote: > On Thu, Feb 09, 2017 at 07:54:05PM +0100, Uladzislau Rezki wrote: > >> > Does this patch make an actual difference, if so how much and with >> > what workload? >> > >> Yes, it does. I see a slight improvement when it comes to frame drops >> (in my case drops per/two seconds). Basically a test case is left finger >> swipe on the display (21 times, duration is 2 seconds + 1 second sleep >> between iterations): >> >> 0 Framedrops: 7 5 >> 1 Framedrops: 5 3 >> 2 Framedrops: 8 5 >> 3 Framedrops: 4 5 >> 4 Framedrops: 3 3 >> 5 Framedrops: 6 4 >> 6 Framedrops: 3 2 >> 7 Framedrops: 3 4 >> 8 Framedrops: 5 3 >> 9 Framedrops: 3 3 >> 10 Framedrops: 7 4 >> 11 Framedrops: 3 4 >> 12 Framedrops: 3 3 >> 13 Framedrops: 3 3 >> 14 Framedrops: 3 5 >> 15 Framedrops: 7 3 >> 16 Framedrops: 5 3 >> 17 Framedrops: 3 2 >> 18 Framedrops: 5 3 >> 19 Framedrops: 4 3 >> 20 Framedrops: 3 2 >> >> max is 8 vs 5; min is 2 vs 3. >> >> As for applied load, it is not significant and i would say is "light". > > So that is useful information that should have been in the Changelog. > > OK, can you respin this patch with adjusted Changelog and taking Mike's > feedback? > Yes, i will prepare a patch accordingly, no problem.
> > Also, I worry about the effects of this on !PREEMPT kernels, the first > hunk (which explicitly states is about latency) should be under > CONFIG_PREEMPT to match the similar case we already have in > detach_tasks(). > > But your second hunk, which ignores the actual load of tasks in favour > of just moving _something_ already, is utterly dangerous if not coupled > with these two other conditions, so arguably that too should be under > CONFIG_PREEMPT. > I see your point. Will round both with CONFIG_PREEMPT. -- Uladzislau Rezki
