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Fri, 18 Jun 2021 18:17:57 -0700 (PDT) MIME-Version: 1.0 References: <475cbc62-a430-2c60-34cc-72ea8baebf2c@linux.intel.com> <82ffac56-e3fb-2d2d-1601-64130310bfc1@linux.intel.com> In-Reply-To: From: Shakeel Butt Date: Fri, 18 Jun 2021 18:17:46 -0700 Message-ID: Subject: Re: [LSF/MM TOPIC] Tiered memory accounting and management To: Tim Chen Cc: Yang Shi , lsf-pc@lists.linux-foundation.org, Linux MM , Michal Hocko , Dan Williams , Dave Hansen , David Rientjes , Wei Xu , Greg Thelen Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=google.com header.s=20161025 header.b=fsD7xxTA; spf=pass (imf14.hostedemail.com: domain of shakeelb@google.com designates 209.85.167.47 as permitted sender) smtp.mailfrom=shakeelb@google.com; dmarc=pass (policy=reject) header.from=google.com X-Stat-Signature: qzczo3psk5ajz5yj13g3bfexf8j1x95k X-Rspamd-Queue-Id: 526A4C0201DB X-Rspamd-Server: rspam06 X-HE-Tag: 1624065479-298653 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jun 18, 2021 at 5:56 PM Tim Chen wrote: > [...] > >> > >> If I understand what you are saying is you desire the kernel to provide > >> the interface to expose performance information like > >> "X% of accesses of high priority jobs is from high tier", > > > > I think we can estimate "X% of accesses to high tier" using existing > > perf/PMU counters. So, no new interface. > > Using a perf counter will be okay to do for user space daemon, but I > think there will be objections from people that the kernel > take away a perf counter to collect perf data in kernel. > This is one possible policy. I would not focus too much on it unless someone says they want exactly that. In that case we can brainstorm how to provide general infrastructure to enforce such policies. Basically this is like an SLO and the violation triggers the balancing (which can be in use space or kernel and a separate discussion).