Hello On 26 August 2013 15:51, Michal Suchanek <hramrach@xxxxxxxxx> wrote: > On 12 March 2013 03:15, Hillf Danton <dhillf@xxxxxxxxx> wrote: >>>On 11 March 2013 13:15, Michal Suchanek <hramrach@xxxxxxxxx> wrote: >>>>On 8 February 2013 17:31, Michal Suchanek <hramrach@xxxxxxxxx> wrote: >>>> Hello, >>>> >>>> I am dealing with VM disk images and performing something like wiping >>>> free space to prepare image for compressing and storing on server or >>>> copying it to external USB disk causes >>>> >>>> 1) system lockup in order of a few tens of seconds when all CPU cores >>>> are 100% used by system and the machine is basicaly unusable >>>> >>>> 2) oom killer killing processes >>>> >>>> This all on system with 8G ram so there should be plenty space to work with. >>>> >>>> This happens with kernels 3.6.4 or 3.7.1 >>>> >>>> With earlier kernel versions (some 3.0 or 3.2 kernels) this was not a >>>> problem even with less ram. >>>> >>>> I have vm.swappiness = 0 set for a long time already. >>>> >>>> >>>I did some testing with 3.7.1 and with swappiness as much as 75 the >>>kernel still causes all cores to loop somewhere in system when writing >>>lots of data to disk. >>> >>>With swappiness as much as 90 processes still get killed on large disk writes. >>> >>>Given that the max is 100 the interval in which mm works at all is >>>going to be very narrow, less than 10% of the paramater range. This is >>>a severe regression as is the cpu time consumed by the kernel. >>> >>>The io scheduler is the default cfq. >>> >>>If you have any idea what to try other than downgrading to an earlier >>>unaffected kernel I would like to hear. >>> >> Can you try commit 3cf23841b4b7(mm/vmscan.c: avoid possible >> deadlock caused by too_many_isolated())? >> >> Or try 3.8 and/or 3.9, additionally? >> > > Hello, > > with deadline IO scheduler I experience this issue less often but it > still happens. > > I am on 3.9.6 Debian kernel so 3.8 did not fix this problem. > > Do you have some idea what to log so that useful information about the > lockup is gathered? > This appears to be fixed in vanilla 3.11 kernel. I still get short intermittent lockups and cpu usage spikes up to 20% on a core but nowhere near the minute+ long lockups with all cores 100% on earlier kernels. Thanks Michal -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>