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[195.38.112.2]) by smtp.gmail.com with ESMTPSA id t5-20020a170906a10500b00a46af5f023bsm587463ejy.202.2024.03.28.03.34.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Mar 2024 03:34:21 -0700 (PDT) Sender: Ingo Molnar Date: Thu, 28 Mar 2024 11:34:19 +0100 From: Ingo Molnar To: Shrikanth Hegde Cc: peterz@infradead.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, qyousef@layalina.io, linux-kernel@vger.kernel.org, vschneid@redhat.com Subject: Re: [PATCH v3 0/2] sched: Minor changes for rd->overload access Message-ID: References: <20240325054505.201995-1-sshegde@linux.ibm.com> <3c92c18b-6a19-4477-9972-1219c29b3d71@linux.ibm.com> <38c39ea6-21df-44e9-96e7-6f6fd35822a7@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <38c39ea6-21df-44e9-96e7-6f6fd35822a7@linux.ibm.com> * Shrikanth Hegde wrote: > > > On 3/26/24 1:30 PM, Ingo Molnar wrote: > > > > * Shrikanth Hegde wrote: > > > >> > >> > >> On 3/25/24 4:06 PM, Ingo Molnar wrote: > >>> > >>> * Shrikanth Hegde wrote: > >>> > >>>> v2 -> v3: > >>>> - Wrapped check for value change inside ser_rd_overload_status > >>>> as suggested by Qais. > >>>> - Added reviewed-by tags. > >>>> > >>>> v1 -> v2: > >>>> - dropped Fixes tag. > >>>> - Added one of the perf probes in the changelog for reference. > >>>> - Added reviewed-by tags. > >>>> > >>>> tl;dr > >>>> When running workloads in large systems, it was observed that access to > >>>> rd->overload was taking time. It would be better to check the value > >>>> before updating since value changes less often. Patch 1/2 does that. > >>>> With patch updates happen only if necessary. CPU Bus traffic reduced a > >>>> bit. No significant gains in workload performance. > >>> > >>> Could you please post this against the latest scheduler tree, ie. tip:sched/core? > >>> > >>> Thanks, > >>> > >>> Ingo > >> > >> Hi Ingo. I had mentioned the same in cover letter. Sorry if I didn't > >> mention it in the correct place. > >> > >> *These patches depend on below to be applied first* > >> https://lore.kernel.org/all/20240307085725.444486-1-sshegde@linux.ibm.com/ > >> > >> After that the above patch would apply. > > Hi Ingo. > > These two patches apply cleanly now to sched/core. > > 7a9dd7ef946c (HEAD -> sched/core) sched/fair: Use helper functions to access rd->overload > 4f24aa918558 sched/fair: Check rd->overload value before update > c829d6818b60 (origin/sched/core) sched/fair: Simplify the continue_balancing logic in sched_balance_newidle() > d0f5d3cefc25 sched/fair: Introduce is_rd_overutilized() helper function to access root_domain::overutilized I've applied them, but note that there were quite a few avoidable typos and grammar mistakes in the changelogs. Please always review what you've submitted versus what I have applied and try to learn from that: I almost invariable have to edit some detail to make the changelog more presentable... Could you please take more care with future patches? I also renamed the accessor functions in the second patch to: get_rd_overload() set_rd_overload() Plus I've applied a patch to rename ::overload to ::overloaded. It is silly to use an ambiguous noun instead of a clear adjective when naming such a flag ... Thanks, Ingo