Hi Nitin, linux-mm list, Any ideas or comments on the problem I encountered and on the question from Tony below? Is it possible to have CONFIG_COMPACTION not wake up systems unnecessarily, or should it perhaps be disabled for systems where power consumption is an issue? Thanks, Regards, Merlijn PS: I already earlier noted in this thread that setting "sysctl -w vm.compaction_proactiveness=0" does not solve the problem, as the system stills is kept awake by CONFIG_COMPACTION. On 10/12/2021 08:20, Tony Lindgren wrote: > Hi, > > * Merlijn Wajer <merlijn@xxxxxxxxxx> [211210 00:34]: >> Hi, >> >> I've spent the day bisecting what exact commit prevented the Nokia N900 >> from entering the OFF sleep state (between v5.8 and v5.9), and it this >> commit: >> >>> # first bad commit: [facdaa917c4d5a376d09d25865f5a863f906234a] mm: proactive compaction >> >> The git tree prior to that commit can idle at about ~27mW in OFF mode, >> and it will often remain in that mode for prolonged amounts of time >> (easily 30 seconds, depending on running userspace). Which the above >> commit applied, the Nokia N900 almost never hits OFF mode any more. This >> would suggest at least to disable CONFIG_COMPACTION, perhaps in >> omap2plus_defconfig? I suspect this might cause idle problems beyond the >> Nokia N900, too. > > Nice find, adding Nitin to Cc as well. Nitin, can we somehow avoid the > timers for CONFIG_COMPACTION on an idle system to prevent waking up the > system unnecessarily? > > Not sure if sysctl -w vm.compaction_proactiveness=0 is enough to disable > compaction for idle, maybe also the HPAGE_FRAG_CHECK_INTERVAL_MSEC = 500 > at ms also causes extra wake-ups? > > Regards, > > Tony > >> Maybe nothing needs to be done here other than disable the config option >> -- but I wanted to share this in case others are trying to figure out >> what happened to their battery life. :-) >> >> There seem be more power regressions since then (at least on 5.15 there >> is more blocking proper idle), so I'll try to find those as well, but if >> this commit is reverted (or CONFIG_COMPACTION=n is in .config - probably >> easier) on top of v5.9 the system seems to idle fine. >> >>> # grep ^core_pwrdm /sys/kernel/debug/pm_debug/count | cut -d',' -f2, >>> OFF:16,RET:2 >> >> Hope this helps someone... >> >> Regards, >> Merlijn >> >> PS: v5.10 seems to use another 19mW if panel_sony_acx565akm is loaded >> even when display is not active (maybe it doesn't suspend or something? >> - could be fixed later, just noticed it for v5.10). I load it initially >> to idle the display, but until I rmmod the modules, the module uses >> quite a bit more power. This problem is not present in v5.9, so that is >> another thing to chase down I guess... And then v5.15 uses another 12mW >> more, for not yet uncovered reasons)
