Date: Wed, 25 Nov 2015 11:30:48 -0500 (EST)
Message-Id: <20151125.113048.45218641761530031.davem@davemloft.net>
To: hannes@cmpxchg.org
Cc: akpm@linux-foundation.org, vdavydov@virtuozzo.com, mhocko@suse.cz,
        tj@kernel.org, eric.dumazet@gmail.com, netdev@vger.kernel.org,
        linux-mm@kvack.org, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 13/13] mm: memcontrol: hook up vmpressure to socket
 pressure
From: David Miller <davem@davemloft.net>
In-Reply-To: <20151124215940.GB1373@cmpxchg.org>
References: <1448401925-22501-1-git-send-email-hannes@cmpxchg.org>
	<20151124215940.GB1373@cmpxchg.org>
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1552
Lines: 32

From: Johannes Weiner <hannes@cmpxchg.org>
Date: Tue, 24 Nov 2015 16:59:40 -0500

> Let the networking stack know when a memcg is under reclaim pressure
> so that it can clamp its transmit windows accordingly.
> 
> Whenever the reclaim efficiency of a cgroup's LRU lists drops low
> enough for a MEDIUM or HIGH vmpressure event to occur, assert a
> pressure state in the socket and tcp memory code that tells it to curb
> consumption growth from sockets associated with said control group.
> 
> Traditionally, vmpressure reports for the entire subtree of a memcg
> under pressure, which drops useful information on the individual
> groups reclaimed. However, it's too late to change the userinterface,
> so add a second reporting mode that reports on the level of reclaim
> instead of at the level of pressure, and use that report for sockets.
> 
> vmpressure events are naturally edge triggered, so for hysteresis
> assert socket pressure for a second to allow for subsequent vmpressure
> events to occur before letting the socket code return to normal.
> 
> This will likely need finetuning for a wider variety of workloads, but
> for now stick to the vmpressure presets and keep hysteresis simple.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: David S. Miller <davem@davemloft.net>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/