All of lore.kernel.org
 help / color / mirror / Atom feed
From: Johannes Weiner <hannes@cmpxchg.org>
To: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] radix-tree: account nodes to memcg only if explicitly requested
Date: Mon, 1 Aug 2016 13:14:35 -0400	[thread overview]
Message-ID: <20160801171435.GA8724@cmpxchg.org> (raw)
In-Reply-To: <20160801160605.GA13263@esperanza>

On Mon, Aug 01, 2016 at 07:06:05PM +0300, Vladimir Davydov wrote:
> On Mon, Aug 01, 2016 at 11:24:09AM -0400, Johannes Weiner wrote:
> > On Mon, Aug 01, 2016 at 04:13:08PM +0300, Vladimir Davydov wrote:
> > > @@ -351,6 +351,12 @@ static int __radix_tree_preload(gfp_t gfp_mask, int nr)
> > >  	struct radix_tree_node *node;
> > >  	int ret = -ENOMEM;
> > >  
> > > +	/*
> > > +	 * Nodes preloaded by one cgroup can be be used by another cgroup, so
> > > +	 * they should never be accounted to any particular memory cgroup.
> > > +	 */
> > > +	gfp_mask &= ~__GFP_ACCOUNT;
> > 
> > But *all* page cache radix tree nodes are allocated from inside the
> > preload code, since the tree insertions need mapping->tree_lock. So
> > this would effectively disable accounting of the biggest radix tree
> > consumer in the kernel, no?
> 
> No, that's not how accounting of radix tree nodes works. We never
> account preloaded nodes, because this could result in a node accounted
> to one cgroup used by an unrelated cgroup. Instead we always try to
> kmalloc a node on insertion falling back on preloads only if kmalloc
> fails - see commit 58e698af4c634 ("radix-tree: account radix_tree_node
> to memory cgroup").

You are right, I forgot we are doing this. The patch makes sense then.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] radix-tree: account nodes to memcg only if explicitly requested
Date: Mon, 1 Aug 2016 13:14:35 -0400	[thread overview]
Message-ID: <20160801171435.GA8724@cmpxchg.org> (raw)
In-Reply-To: <20160801160605.GA13263@esperanza>

On Mon, Aug 01, 2016 at 07:06:05PM +0300, Vladimir Davydov wrote:
> On Mon, Aug 01, 2016 at 11:24:09AM -0400, Johannes Weiner wrote:
> > On Mon, Aug 01, 2016 at 04:13:08PM +0300, Vladimir Davydov wrote:
> > > @@ -351,6 +351,12 @@ static int __radix_tree_preload(gfp_t gfp_mask, int nr)
> > >  	struct radix_tree_node *node;
> > >  	int ret = -ENOMEM;
> > >  
> > > +	/*
> > > +	 * Nodes preloaded by one cgroup can be be used by another cgroup, so
> > > +	 * they should never be accounted to any particular memory cgroup.
> > > +	 */
> > > +	gfp_mask &= ~__GFP_ACCOUNT;
> > 
> > But *all* page cache radix tree nodes are allocated from inside the
> > preload code, since the tree insertions need mapping->tree_lock. So
> > this would effectively disable accounting of the biggest radix tree
> > consumer in the kernel, no?
> 
> No, that's not how accounting of radix tree nodes works. We never
> account preloaded nodes, because this could result in a node accounted
> to one cgroup used by an unrelated cgroup. Instead we always try to
> kmalloc a node on insertion falling back on preloads only if kmalloc
> fails - see commit 58e698af4c634 ("radix-tree: account radix_tree_node
> to memory cgroup").

You are right, I forgot we are doing this. The patch makes sense then.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  reply	other threads:[~2016-08-01 17:15 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-01 13:13 [PATCH] radix-tree: account nodes to memcg only if explicitly requested Vladimir Davydov
2016-08-01 13:13 ` Vladimir Davydov
2016-08-01 15:24 ` Johannes Weiner
2016-08-01 15:24   ` Johannes Weiner
2016-08-01 16:06   ` Vladimir Davydov
2016-08-01 16:06     ` Vladimir Davydov
2016-08-01 17:14     ` Johannes Weiner [this message]
2016-08-01 17:14       ` Johannes Weiner
2016-08-02 11:51 ` Michal Hocko
2016-08-02 11:51   ` Michal Hocko
2016-08-02 12:42   ` Vladimir Davydov
2016-08-02 12:42     ` Vladimir Davydov
2016-08-02 12:46     ` Michal Hocko
2016-08-02 12:46       ` Michal Hocko
2016-08-02 18:51       ` Andrew Morton
2016-08-02 18:51         ` Andrew Morton

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20160801171435.GA8724@cmpxchg.org \
    --to=hannes@cmpxchg.org \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=vdavydov@virtuozzo.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.