From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCHv2 8/8] zsmalloc: register a shrinker to trigger auto-compaction
Date: Thu, 18 Jun 2015 12:01:36 +0900 [thread overview]
Message-ID: <20150618030136.GD3422@swordfish> (raw)
In-Reply-To: <20150618023906.GC3422@swordfish>
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
WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCHv2 8/8] zsmalloc: register a shrinker to trigger auto-compaction
Date: Thu, 18 Jun 2015 12:01:36 +0900 [thread overview]
Message-ID: <20150618030136.GD3422@swordfish> (raw)
In-Reply-To: <20150618023906.GC3422@swordfish>
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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next prev parent reply other threads:[~2015-06-18 3:01 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-05 12:03 [RFC][PATCHv2 0/8] introduce automatic pool compaction Sergey Senozhatsky
2015-06-05 12:03 ` Sergey Senozhatsky
2015-06-05 12:03 ` [RFC][PATCHv2 1/8] zsmalloc: drop unused variable `nr_to_migrate' Sergey Senozhatsky
2015-06-05 12:03 ` Sergey Senozhatsky
2015-06-05 12:03 ` [RFC][PATCHv2 2/8] zsmalloc: partial page ordering within a fullness_list Sergey Senozhatsky
2015-06-05 12:03 ` Sergey Senozhatsky
2015-06-16 13:19 ` Minchan Kim
2015-06-16 13:19 ` Minchan Kim
2015-06-16 14:30 ` Sergey Senozhatsky
2015-06-16 14:30 ` Sergey Senozhatsky
2015-06-05 12:03 ` [RFC][PATCHv2 3/8] zsmalloc: lower ZS_ALMOST_FULL waterline Sergey Senozhatsky
2015-06-05 12:03 ` Sergey Senozhatsky
2015-06-16 13:37 ` Minchan Kim
2015-06-16 13:37 ` Minchan Kim
2015-06-16 14:35 ` Sergey Senozhatsky
2015-06-16 14:35 ` Sergey Senozhatsky
2015-06-05 12:03 ` [RFC][PATCHv2 4/8] zsmalloc: always keep per-class stats Sergey Senozhatsky
2015-06-05 12:03 ` Sergey Senozhatsky
2015-06-05 12:03 ` [RFC][PATCHv2 5/8] zsmalloc: introduce zs_can_compact() function Sergey Senozhatsky
2015-06-05 12:03 ` Sergey Senozhatsky
2015-06-16 14:19 ` Minchan Kim
2015-06-16 14:19 ` Minchan Kim
2015-06-16 14:41 ` Sergey Senozhatsky
2015-06-16 14:41 ` Sergey Senozhatsky
2015-06-05 12:03 ` [RFC][PATCHv2 6/8] zsmalloc: cosmetic compaction code adjustments Sergey Senozhatsky
2015-06-05 12:03 ` Sergey Senozhatsky
2015-06-05 12:03 ` [RFC][PATCHv2 7/8] zsmalloc/zram: move `num_migrated' to zs_pool Sergey Senozhatsky
2015-06-05 12:03 ` Sergey Senozhatsky
2015-06-05 12:03 ` [RFC][PATCHv2 8/8] zsmalloc: register a shrinker to trigger auto-compaction Sergey Senozhatsky
2015-06-05 12:03 ` Sergey Senozhatsky
2015-06-16 14:47 ` Minchan Kim
2015-06-16 14:47 ` Minchan Kim
2015-06-16 15:45 ` Sergey Senozhatsky
2015-06-16 15:45 ` Sergey Senozhatsky
2015-06-18 1:50 ` Minchan Kim
2015-06-18 1:50 ` Minchan Kim
2015-06-18 2:41 ` Sergey Senozhatsky
2015-06-18 2:41 ` Sergey Senozhatsky
2015-06-18 3:01 ` Sergey Senozhatsky [this message]
2015-06-18 3:01 ` Sergey Senozhatsky
2015-06-18 3:46 ` Minchan Kim
2015-06-18 3:46 ` Minchan Kim
2015-06-18 3:39 ` Minchan Kim
2015-06-18 3:39 ` Minchan Kim
2015-06-18 3:58 ` Sergey Senozhatsky
2015-06-18 3:58 ` Sergey Senozhatsky
2015-06-17 7:11 ` Sergey Senozhatsky
2015-06-17 7:11 ` Sergey Senozhatsky
2015-06-10 0:04 ` [RFC][PATCHv2 0/8] introduce automatic pool compaction Minchan Kim
2015-06-10 0:04 ` Minchan Kim
2015-06-10 0:07 ` Sergey Senozhatsky
2015-06-10 0:07 ` Sergey Senozhatsky
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