Re: [PATCH resend] memcg: introduce per-memcg reclaim interface

From: "Michal Koutný" <mkoutny@suse.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Wei Xu <weixugc@google.com>, Johannes Weiner <hannes@cmpxchg.org>,
	Yosry Ahmed <yosryahmed@google.com>,
	Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	David Rientjes <rientjes@google.com>, Tejun Heo <tj@kernel.org>,
	Zefan Li <lizefan.x@bytedance.com>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Cgroups <cgroups@vger.kernel.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>, Jonathan Corbet <corbet@lwn.net>,
	Yu Zhao <yuzhao@google.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Greg Thelen <gthelen@google.com>
Subject: Re: [PATCH resend] memcg: introduce per-memcg reclaim interface
Date: Tue, 5 Apr 2022 12:09:06 +0200	[thread overview]
Message-ID: <20220405100906.GB13806@blackbody.suse.cz> (raw)
In-Reply-To: <CALvZod4-fKfv6vbZPZ3nCE=Bue4FUnC+9t27wsznmyd+JKgDbg@mail.gmail.com>

On Mon, Apr 04, 2022 at 10:08:43AM -0700, Shakeel Butt <shakeelb@google.com> wrote:
> What would be the challenge on returning the number of bytes reclaimed
> through cgroup interface?

You'd need an object that represents the write size:

> bfd = open("/sys/kernel/mm/reclaim/balloon", O_RDWR);
> dprintf(bfd, "type=file nodemask=1-2 timeout=30\n")
> 
> fd = open("/sys/kernel/fs/cgroup/foo/memory.reclaim", O_WRONLY);
> reclaimed = splice(bfd, NULL, fd, NULL, reclaim_size);

(I'm joking with this API but it is a resembling concept.)

Michal