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From:   Shakeel Butt <shakeelb@google.com>
Date:   Mon, 4 Apr 2022 10:08:43 -0700
Message-ID: <CALvZod4-fKfv6vbZPZ3nCE=Bue4FUnC+9t27wsznmyd+JKgDbg@mail.gmail.com>
Subject: Re: [PATCH resend] memcg: introduce per-memcg reclaim interface
To:     Wei Xu <weixugc@google.com>
Cc:     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>
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On Fri, Apr 1, 2022 at 1:14 PM Wei Xu <weixugc@google.com> wrote:
>
[...]
>
> -EAGAIN sounds good, too.  Given that the userspace requests to
> reclaim a specified number of bytes, I think it is generally better to
> tell the userspace whether the request has been successfully
> fulfilled. Ideally, it would be even better to return how many bytes
> that have been reclaimed, though that is not easy to do through the
> cgroup interface.

What would be the challenge on returning the number of bytes reclaimed
through cgroup interface?