Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 14 Dec 2018 12:32:41 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Andrea Arcangeli <aarcange@redhat.com>
Cc:     David Rientjes <rientjes@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        mgorman@techsingularity.net, Vlastimil Babka <vbabka@suse.cz>,
        ying.huang@intel.com, s.priebe@profihost.ag,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        alex.williamson@redhat.com, lkp@01.org, kirill@shutemov.name,
        Andrew Morton <akpm@linux-foundation.org>,
        zi.yan@cs.rutgers.edu
Subject: Re: [LKP] [mm] ac5b2c1891: vm-scalability.throughput -61.3%
 regression
Message-ID: <20181214113241.GC5343@dhcp22.suse.cz>
References: <20181205233632.GE11899@redhat.com>
 <CAHk-=wguXjkbK8BUU998s7HD7AXJgBkuc9JmuNxiN7uGQyfSfQ@mail.gmail.com>
 <CAHk-=wjm9V843eg0uesMrxKnCCq7UfWn8VJ+z-cNztb_0fVW6A@mail.gmail.com>
 <alpine.DEB.2.21.1812061505010.162675@chino.kir.corp.google.com>
 <CAHk-=wjVuLjZ1Wr52W=hNqh=_8gbzuKA+YpsVb4NBHCJsE6cyA@mail.gmail.com>
 <alpine.DEB.2.21.1812091538310.215735@chino.kir.corp.google.com>
 <20181210044916.GC24097@redhat.com>
 <alpine.DEB.2.21.1812111609060.255489@chino.kir.corp.google.com>
 <20181212095051.GO1286@dhcp22.suse.cz>
 <20181212170016.GG1130@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20181212170016.GG1130@redhat.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed 12-12-18 12:00:16, Andrea Arcangeli wrote:
[...]
> Adding MADV_THISNODE/MADV_NODE_RECLAIM, will guarantee his proprietary
> software binary will run at maximum performance without cache
> interference, and he's happy to accept the risk of massive slowdown in
> case the local node is truly OOM. The fallback, despite very
> inefficient, will still happen without OOM killer triggering.

I believe this fits much better into a MPOL_$FOO rather than MADV_$FOO.
But other than that I full agree. There are reasonable usecases for the
node reclaim like behavior. As a bonus you do not get local node only
but all nodes within reclaim distance as well.
-- 
Michal Hocko
SUSE Labs