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[198.145.29.99]) by mx.google.com with ESMTPS id u15si51473680pgn.178.2019.08.07.13.01.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 07 Aug 2019 13:01:23 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=zQWA7F1K; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6D7B42229C; Wed, 7 Aug 2019 20:01:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565208083; bh=4Y+9zhlp+p8rLuzDnvz16xcsN6RE4cU24OrOaFTWccE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=zQWA7F1KoIQRCIl1yVyS0BiJUwsrwYEryJKxMHNxcX6ONB8eZ93zxVmeDQ44zmmr7 94PMczCgAY0emIRaZfVAe7SJ/fxtD+5a/tCkNgG8bpb7LPhysLSpabBlToJlvBBdXz 27kDL9DLZKISnabXM7rW3N8cStMFHWeqYCj5Xb7E= Date: Wed, 7 Aug 2019 13:01:22 -0700 From: Andrew Morton To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, Alexey Dobriyan , Borislav Petkov , Brendan Gregg , Catalin Marinas , Christian Hansen , dancol@google.com, fmayer@google.com, "H. Peter Anvin" , Ingo Molnar , Jonathan Corbet , Kees Cook , kernel-team@android.com, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Mike Rapoport , minchan@kernel.org, namhyung@google.com, paulmck@linux.ibm.com, Robin Murphy , Roman Gushchin , Stephen Rothwell , surenb@google.com, Thomas Gleixner , tkjos@google.com, Vladimir Davydov , Vlastimil Babka , Will Deacon , Brendan Gregg Subject: Re: [PATCH v4 1/5] mm/page_idle: Add per-pid idle page tracking using virtual indexing Message-Id: <20190807130122.f148548c05ec07e7b716457e@linux-foundation.org> In-Reply-To: <20190807100013.GC169551@google.com> References: <20190805170451.26009-1-joel@joelfernandes.org> <20190806151921.edec128271caccb5214fc1bd@linux-foundation.org> <20190807100013.GC169551@google.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 7 Aug 2019 06:00:13 -0400 Joel Fernandes wrote: > > > 8 files changed, 376 insertions(+), 45 deletions(-) > > > > Quite a lot of new code unconditionally added to major architectures. > > Are we confident that everyone will want this feature? > > I did not follow, could you clarify more? All of this diff stat is not to > architecture code: My point is that the patchset adds a lot of new code with no way in which users can opt out. Almost everyone gets a fatter kernel - how many of those users will actually benefit from it? If "not many" then shouldn't we be making it Kconfigurable? Are there userspace tools which present this info to users or which provide monitoring of some form? Do major distros ship those tools? Do people use them? etcetera.