Messages in this thread | | | Date | Thu, 18 Jun 2015 12:01:36 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [RFC][PATCHv2 8/8] zsmalloc: register a shrinker to trigger auto-compaction |
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On (06/18/15 11:41), Sergey Senozhatsky wrote: [..] > > My concern is not a compacion overhead but higher memory footprint > > consumed by zram in reserved memory. > > It might hang system if zram used up reserved memory of system with > > ALLOC_NO_WATERMARKS. With auto-compaction, userspace has a higher chance > > to use more memory with uncompressible pages or file-backed pages > > so zram-swap can use more reserved memory. We need to evaluate it, I think. > >
a couple of _not really related_ ideas that I want to voice.
(a) I'm thinking of extending zramX/compact attr. right now it's WO, and I think it makes sense to make it RW: ->write will trigger compaction ->read will return estimated number of bytes "zs_can_compact() * pages per zspage * page_size" that can be freed. so user-space will have at least minimal idea whether compaction is reasonable. but sure, this is racy and in general case things may change between `cat compact` and `echo 1 > compact`.
(b) adding a knob (yeah, like we don't have enough knobs already :-)) that will allow 'enable/disable auto compaction'.
-ss
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