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[209.85.220.41]) by mx.google.com with SMTPS id c13sor17505255pls.34.2019.04.24.09.36.52 for (Google Transport Security); Wed, 24 Apr 2019 09:36:52 -0700 (PDT) Received-SPF: pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; Authentication-Results: mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b=D4Fw+Yst; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.41 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=cmpxchg.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=bU/jX4EW0n/qwLCy74iol1YUkyqzsbWOTtyq6RpkK+o=; b=D4Fw+YstAFvEcLOXoz0+EOCMKbdFRz9+xSQITiW9brI/gN8iTqnLu8B5LRBg+QVQTw JYlRewnLVVwhUf5CPnOVPDNN4Z7pZKlQf3caK9zC/yjKUew/clyyCpkpJgAw0DAwGiBV Oh6y5cvw4G1nqWMa9SlFCcCN3Dnhz45SjnkmhhuzFWNWI0HXdVUrA1ODHEnOAKmkJemi hsHdPiEebqUnVcIAWySSWmkAwqyUvIzVUAmL+rmYqwg1uh3dpm06AIspDs5u+d8k9cYG 87HfXHJSOW6CSkFGOYaZ7FsrQw+Q+6E+S+3lVuaW2kpNlmxeoyIG4AIpA3kviqiYYwDQ 2SFw== X-Google-Smtp-Source: APXvYqz3ZsYjN/GMH6XJGU5WPREplJK5uhzjVbCbvGUwH8+cV6tc/eInXh1rwPLRoUunccagzkonPA== X-Received: by 2002:a17:902:a5ca:: with SMTP id t10mr33803404plq.234.1556123812238; Wed, 24 Apr 2019 09:36:52 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::3:3dcf]) by smtp.gmail.com with ESMTPSA id s20sm23146257pgs.39.2019.04.24.09.36.50 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 24 Apr 2019 09:36:51 -0700 (PDT) Date: Wed, 24 Apr 2019 12:36:49 -0400 From: Johannes Weiner To: Suren Baghdasaryan Cc: Luigi Semenzato , Linux Memory Management List Subject: Re: PSI vs. CPU overhead for client computing Message-ID: <20190424163649.GA14187@cmpxchg.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.002627, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Apr 23, 2019 at 03:04:16PM -0700, Suren Baghdasaryan wrote: > On Tue, Apr 23, 2019 at 11:58 AM Luigi Semenzato wrote: > > The chrome browser is a multi-process app and there is a lot of IPC. When > > process A is blocked on memory allocation, it cannot respond to IPC > > from process B, thus effectively both processes are blocked on > > allocation, but we don't see that. > > I don't think PSI would account such an indirect stall when A is > waiting for B and B is blocked on memory access. B's stall will be > accounted for but I don't think A's blocked time will go into PSI > calculations. The process inter-dependencies are probably out of scope > for PSI. Well, yes and no. We don't do explicit dependency tracking, but when A is waiting on B it's also not considered productive, so it doesn't factor into the equation. psi will see B blocked on memory and no other productive processes, which means FULL state until B resumes.