On 01/26/2015 10:58 PM, Michal Hocko wrote:
On Sat 17-01-15 13:48:34, Christoph Lameter wrote:
On Sat, 17 Jan 2015, Vinayak Menon wrote:
which had not updated the vmstat_diff. This CPU was in idle for around 30
secs. When I looked at the tvec base for this CPU, the timer associated with
vmstat_update had its expiry time less than current jiffies. This timer had
its deferrable flag set, and was tied to the next non-deferrable timer in the
We can remove the deferrrable flag now since the vmstat threads are only
activated as necessary with the recent changes. Looks like this could fix
your issue?
OK, I have checked the history and the deferrable behavior has been
introduced by 39bf6270f524 (VM statistics: Make timer deferrable) which
hasn't offered any numbers which would justify the change. So I think it
would be a good idea to revert this one as it can clearly cause issues.
Could you retest with this change? It still wouldn't help with the
highly overloaded workqueues but that sounds like a bigger change and
this one sounds like quite safe to me so it is a good start.
Sure, I can retest.
Even without highly overloaded workqueues, there can be a delay of HZ in
updating the counters. This means reclaim path can be blocked for a
second or more, when there aren't really any isolated pages. So we need
the fix in too_many_isolated also right ?
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