From: Michal Hocko <mhocko@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
mingo@kernel.org, peterz@infradead.org, jack@suse.cz,
torvalds@linux-foundation.org, kirill.shutemov@linux.intel.com,
hch@infradead.org, ldufour@linux.vnet.ibm.com,
mgorman@techsingularity.net, linux-kernel@vger.kernel.org,
Davidlohr Bueso <dbueso@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>
Subject: Re: [PATCH 16/17] mem/memcg: cache rightmost node
Date: Thu, 27 Jul 2017 09:06:08 +0200 [thread overview]
Message-ID: <20170727070608.GF20970@dhcp22.suse.cz> (raw)
In-Reply-To: <20170726140927.1408d4308795d3e3fdb082c4@linux-foundation.org>
On Wed 26-07-17 14:09:27, Andrew Morton wrote:
> On Wed, 19 Jul 2017 09:50:36 +0200 Michal Hocko <mhocko@kernel.org> wrote:
>
> > [CC Johannes and Vladimir - the whole series is
> > http://lkml.kernel.org/r/20170719014603.19029-1-dave@stgolabs.net]
> >
> > On Tue 18-07-17 18:46:02, Davidlohr Bueso wrote:
> > > Such that we can optimize __mem_cgroup_largest_soft_limit_node().
> > > The only overhead is the extra footprint for the cached pointer,
> > > but this should not be an issue for mem_cgroup_tree_per_node.
> >
> > The soft limit reclaim and the associated tree manipulation is not worth
> > touching/optimizing IMHO. We strongly discourage anybody configuring
> > soft limit because of the way how it is implemented and disruptive.
>
> I'm inclined to merge this. Unless we plan to actually remove the code
> "soon",
this is not going to happen. It is a user visible interface so we will
have to maintain it as long as cgroup v1 interface is available
> I think it's best to continue to improve it. Improving
> performance may never matter to anyone, but there is benefit in keeping
> up to date with the current interfaces and best practices.
Well, I am not opposing the change I just think it is not worth
bothering. Soft limit reclaim tends to be so expensive (direct limit
down to the soft limit) that a tiny otimization has hard times to help.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2017-07-27 7:06 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-19 1:45 [PATCH -next v4 00/17] rbtree: cache leftmost node internally Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 01/17] " Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 02/17] rbtree: optimize root-check during rebalancing loop Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 03/17] rbtree: add some additional comments for rebalancing cases Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 04/17] lib/rbtree_test.c: make input module parameters Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 05/17] lib/rbtree_test.c: add (inorder) traversal test Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 06/17] lib/rbtree_test.c: support rb_root_cached Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 07/17] sched/fair: replace cfs_rq->rb_leftmost Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 08/17] sched/deadline: replace earliest dl and rq leftmost caching Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 09/17] locking/rtmutex: replace top-waiter and pi_waiters " Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 10/17] block/cfq: replace cfq_rb_root " Davidlohr Bueso
2017-07-19 7:46 ` Jan Kara
2017-07-19 1:45 ` [PATCH 11/17] lib/interval_tree: fast overlap detection Davidlohr Bueso
2017-07-22 17:52 ` Doug Ledford
2017-08-01 17:16 ` Michael S. Tsirkin
2017-07-19 1:45 ` [PATCH 12/17] lib/interval-tree: correct comment wrt generic flavor Davidlohr Bueso
2017-07-19 1:45 ` [PATCH 13/17] procfs: use faster rb_first_cached() Davidlohr Bueso
2017-07-19 1:46 ` [PATCH 14/17] fs/epoll: " Davidlohr Bueso
2017-07-19 1:46 ` [PATCH 15/17] fs/ext4: use cached rbtrees Davidlohr Bueso
2017-07-19 7:40 ` Jan Kara
2017-07-19 22:50 ` Davidlohr Bueso
2017-07-19 1:46 ` [PATCH 16/17] mem/memcg: cache rightmost node Davidlohr Bueso
2017-07-19 7:50 ` Michal Hocko
2017-07-26 21:09 ` Andrew Morton
2017-07-27 7:06 ` Michal Hocko [this message]
2017-07-19 1:46 ` [PATCH 17/17] block/cfq: cache rightmost rb_node Davidlohr Bueso
2017-07-19 7:59 ` Jan Kara
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