From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 04/11] sched,x86: Enable Turbo Boost Max Technology Date: Wed, 24 Aug 2016 20:08:54 +0200 Message-ID: <20160824180854.GA1398@gmail.com> References: <1471559812-19967-1-git-send-email-srinivas.pandruvada@linux.intel.com> <1471559812-19967-5-git-send-email-srinivas.pandruvada@linux.intel.com> <20160824101853.GA25705@gmail.com> <20160824175057.GA5032@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160824175057.GA5032@linux.intel.com> Sender: linux-acpi-owner@vger.kernel.org To: Tim Chen Cc: Srinivas Pandruvada , mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, rjw@rjwysocki.net, peterz@infradead.org, x86@kernel.org, bp@suse.de, sudeep.holla@arm.com, ak@linux.intel.com, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, alexey.klimov@arm.com, viresh.kumar@linaro.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, lenb@kernel.org, paul.gortmaker@windriver.com, jpoimboe@redhat.com, mcgrof@kernel.org, jgross@suse.com, robert.moore@intel.com, dvyukov@google.com, jeyu@redhat.com, Peter Zijlstra List-Id: linux-pm@vger.kernel.org * Tim Chen wrote: > Ingo, > > This feature will be a clear benefit for client machines and > less clear on servers. > > This feature is most beneficial to single threaded workload running on > a single socket that operates in mostly Turbo mode. Client platform > like Broadwell High End Desktop is the first one that supports it. > Enablng this feature for such platform by default will be a win as it > runs single threaded workload much of the time (10%-15% peformance > upside). > > On the other hand, a heavily loaded server that rarely operates in Turbo > mode will benefit much less from this feature. There is some overhead > incurred by migrating load to the favored cores. Some server folks > have asked us to be cautious here and not to turn on ITMT scheduling > by default. Even so, when the server is lightly loaded, this feature > can still be a win. That said, this is future looking as we don't have > any server with this feature today. > > So if we take the approach to enable this feature by default for only > single node system (using that as a criteria for client), will that seem > reasonable to you? I suppose that would work. Peter, any objections to such an approach? Thanks, Ingo