Messages in this thread | | | From | Michal Suchanek <> | Date | Tue, 12 Mar 2013 10:03:53 +0100 | Subject | Re: doing lots of disk writes causes oom killer to kill processes |
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On 12 March 2013 03:15, Hillf Danton <dhillf@gmail.com> wrote: >>On 11 March 2013 13:15, Michal Suchanek <hramrach@gmail.com> wrote: >>>On 8 February 2013 17:31, Michal Suchanek <hramrach@gmail.com> 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,
in the meantime I tried setting io scheduler to deadline because I remember using that one in my self-built kernels due to cfq breaking some obscure block driver.
With the deadline io scheduler I can set swappiness back to 0 and the system works normally even for moderate amount of IO - restoring disk images from network. This would cause lockups and oom killer running loose with the cfq scheduler.
So I guess I found what breaks the system and it is not so much the kernel version. It's using pre-built kernels with the default scheduler.
Thanks
Michal
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