On (07/10/15 14:21), Minchan Kim wrote:
> > I mean I find your argument that some level of fragmentation
> > can be of use to be valid, to some degree.
>
> The benefit I had in mind was to prevent failure of allocation.
>
Sure. I tested the patch.
cat /sys/block/zram0/mm_stat
3122102272 2882639758 2890366976 0 2969432064 55 79294
cat /sys/block/zram0/stat
7212 0 57696 73 7513254 0 60106032 52096 0 52106 52113
Compaction stats:
[14637.002961] compaction nr:89 (full:528 part:3027) ~= 0.148
Nothing `alarming'.
> > I'm thinking now, does it make sense to try harder here? if we
> > failed to alloc_zspage(), then may be we can try any of unused
> > objects from a 'upper' (larger/next) class? there might be a
> > plenty of them.
>
> I actually thought about that but I didn't have any report from
> community and product division of my compamy until now.
> But with auto-compaction, the chance would be higher than old
> so let's keep an eye on it(I think users can find it easily because
> swap layer emits "write write failure").
>
> If it happens(ie, any report from someone), we could try to compact
> and then if it fails, we could fall back to upper class as a last
> resort.
>
OK.
-ss
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