linux-kernel - Re: [PATCH 02/10] memcg: document cgroup dirty memory interfaces

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Date:	Tue, 5 Oct 2010 15:48:46 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Greg Thelen <gthelen@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	containers@...ts.osdl.org, Andrea Righi <arighi@...eler.com>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Subject: Re: [PATCH 02/10] memcg: document cgroup dirty memory interfaces

On Sun,  3 Oct 2010 23:57:57 -0700
Greg Thelen <gthelen@...gle.com> wrote:

> Document cgroup dirty memory interfaces and statistics.
> 
> Signed-off-by: Andrea Righi <arighi@...eler.com>
> Signed-off-by: Greg Thelen <gthelen@...gle.com>

Nice.

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>





> ---
>  Documentation/cgroups/memory.txt |   37 +++++++++++++++++++++++++++++++++++++
>  1 files changed, 37 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
> index 7781857..eab65e2 100644
> --- a/Documentation/cgroups/memory.txt
> +++ b/Documentation/cgroups/memory.txt
> @@ -385,6 +385,10 @@ mapped_file	- # of bytes of mapped file (includes tmpfs/shmem)
>  pgpgin		- # of pages paged in (equivalent to # of charging events).
>  pgpgout		- # of pages paged out (equivalent to # of uncharging events).
>  swap		- # of bytes of swap usage
> +dirty		- # of bytes that are waiting to get written back to the disk.
> +writeback	- # of bytes that are actively being written back to the disk.
> +nfs		- # of bytes sent to the NFS server, but not yet committed to
> +		the actual storage.
>  inactive_anon	- # of bytes of anonymous memory and swap cache memory on
>  		LRU list.
>  active_anon	- # of bytes of anonymous and swap cache memory on active
> @@ -453,6 +457,39 @@ memory under it will be reclaimed.
>  You can reset failcnt by writing 0 to failcnt file.
>  # echo 0 > .../memory.failcnt
>  
> +5.5 dirty memory
> +
> +Control the maximum amount of dirty pages a cgroup can have at any given time.
> +
> +Limiting dirty memory is like fixing the max amount of dirty (hard to reclaim)
> +page cache used by a cgroup.  So, in case of multiple cgroup writers, they will
> +not be able to consume more than their designated share of dirty pages and will
> +be forced to perform write-out if they cross that limit.
> +
> +The interface is equivalent to the procfs interface: /proc/sys/vm/dirty_*.  It
> +is possible to configure a limit to trigger both a direct writeback or a
> +background writeback performed by per-bdi flusher threads.  The root cgroup
> +memory.dirty_* control files are read-only and match the contents of
> +the /proc/sys/vm/dirty_* files.
> +
> +Per-cgroup dirty limits can be set using the following files in the cgroupfs:
> +
> +- memory.dirty_ratio: the amount of dirty memory (expressed as a percentage of
> +  cgroup memory) at which a process generating dirty pages will itself start
> +  writing out dirty data.
> +
> +- memory.dirty_bytes: the amount of dirty memory (expressed in bytes) in the
> +  cgroup at which a process generating dirty pages will start itself writing out
> +  dirty data.
> +
> +- memory.dirty_background_ratio: the amount of dirty memory of the cgroup
> +  (expressed as a percentage of cgroup memory) at which background writeback
> +  kernel threads will start writing out dirty data.
> +
> +- memory.dirty_background_bytes: the amount of dirty memory (expressed in bytes)
> +  in the cgroup at which background writeback kernel threads will start writing
> +  out dirty data.
> +
>  6. Hierarchy support
>  
>  The memory controller supports a deep hierarchy and hierarchical accounting.
> -- 
> 1.7.1
> 
> 

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