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From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH 03/10] zsmalloc: introduce zs_can_compact() function
Date: Thu, 4 Jun 2015 12:42:30 +0900	[thread overview]
Message-ID: <20150604034230.GH1951@swordfish> (raw)
In-Reply-To: <20150604033014.GG2241@blaptop>

On (06/04/15 12:30), Minchan Kim wrote:
> > -- free objects in class: 5 (free-objs class capacity)
> > -- page1: inuse 2
> > -- page2: inuse 2
> > -- page3: inuse 3
> > -- page4: inuse 2
> 
> What scenario do you have a cocern?
> Could you describe this example more clear?

you mean "how is this even possible"?

well, for example,

make -jX
make clean

can introduce a significant fragmentation. no new objects, just random
objs removal. assuming that we keep some of the objects, allocated during
compilation.

e.g.

...

page1
  allocate baz.so
  allocate foo.o
page2
  allocate bar.o
  allocate foo.so
...
pageN



now `make clean`

page1:
  allocated baz.so
  empty

page2
  empty
  allocated foo.so

...

pageN

in the worst case, every page can turn out to be ALMOST_EMPTY.

	-ss

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  reply	other threads:[~2015-06-04  3:42 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-29 15:05 [RFC][PATCH 00/10] zsmalloc auto-compaction Sergey Senozhatsky
2015-05-29 15:05 ` [RFC][PATCH 01/10] zsmalloc: drop unused variable `nr_to_migrate' Sergey Senozhatsky
2015-06-04  2:04   ` Minchan Kim
2015-06-04  2:10     ` Sergey Senozhatsky
2015-05-29 15:05 ` [RFC][PATCH 02/10] zsmalloc: always keep per-class stats Sergey Senozhatsky
2015-06-04  2:18   ` Minchan Kim
2015-06-04  2:34     ` Sergey Senozhatsky
2015-05-29 15:05 ` [RFC][PATCH 03/10] zsmalloc: introduce zs_can_compact() function Sergey Senozhatsky
2015-06-04  2:55   ` Minchan Kim
2015-06-04  3:15     ` Sergey Senozhatsky
2015-06-04  3:30       ` Minchan Kim
2015-06-04  3:42         ` Sergey Senozhatsky [this message]
2015-06-04  3:50           ` Minchan Kim
2015-06-04  4:19             ` Sergey Senozhatsky
2015-06-04  3:31       ` Sergey Senozhatsky
2015-05-29 15:05 ` [RFC][PATCH 04/10] zsmalloc: cosmetic compaction code adjustments Sergey Senozhatsky
2015-06-04  3:14   ` Minchan Kim
2015-05-29 15:05 ` [RFC][PATCH 05/10] zsmalloc: add `num_migrated' to zs_pool Sergey Senozhatsky
2015-05-29 15:05 ` [RFC][PATCH 06/10] zsmalloc: move compaction functions Sergey Senozhatsky
2015-05-29 15:05 ` [RFC][PATCH 07/10] zsmalloc: introduce auto-compact support Sergey Senozhatsky
2015-06-04  4:57   ` Minchan Kim
2015-06-04  5:30     ` Sergey Senozhatsky
2015-06-04  6:27       ` Minchan Kim
2015-06-04  7:04         ` Minchan Kim
2015-06-04 14:47           ` Sergey Senozhatsky
2015-06-04  7:28         ` Sergey Senozhatsky
2015-05-29 15:05 ` [RFC][PATCH 08/10] zsmalloc: export zs_pool `num_migrated' Sergey Senozhatsky
2015-05-29 15:05 ` [RFC][PATCH 09/10] zram: remove `num_migrated' from zram_stats Sergey Senozhatsky
2015-05-29 15:05 ` [RFC][PATCH 10/10] zsmalloc: lower ZS_ALMOST_FULL waterline Sergey Senozhatsky
2015-06-03  5:09 ` [RFC][PATCH 00/10] zsmalloc auto-compaction Sergey Senozhatsky

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