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Wed, 27 Mar 2024 06:04:59 GMT Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 965885805D; Wed, 27 Mar 2024 06:04:57 +0000 (GMT) Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 900CD5806A; Wed, 27 Mar 2024 06:04:55 +0000 (GMT) Received: from [9.195.42.203] (unknown [9.195.42.203]) by smtpav05.dal12v.mail.ibm.com (Postfix) with ESMTP; Wed, 27 Mar 2024 06:04:55 +0000 (GMT) Message-ID: <38c39ea6-21df-44e9-96e7-6f6fd35822a7@linux.ibm.com> Date: Wed, 27 Mar 2024 11:34:54 +0530 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 0/2] sched: Minor changes for rd->overload access To: Ingo Molnar Cc: peterz@infradead.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, qyousef@layalina.io, linux-kernel@vger.kernel.org, vschneid@redhat.com References: <20240325054505.201995-1-sshegde@linux.ibm.com> <3c92c18b-6a19-4477-9972-1219c29b3d71@linux.ibm.com> From: Shrikanth Hegde Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: IwtaeeRy4nQ0AXIyR4dNGkLzgOnYFdUD X-Proofpoint-ORIG-GUID: ZBQXITSR5lVcSmpSh3qNzp0UgmxNE45W Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-03-27_02,2024-03-21_02,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 phishscore=0 mlxscore=0 malwarescore=0 clxscore=1015 bulkscore=0 adultscore=0 spamscore=0 mlxlogscore=999 impostorscore=0 suspectscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2403210000 definitions=main-2403270037 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 > > OK, I missed that, but I don't really like patch #3 of that other series, > so we'll need to address that first. > That will be a standalone patch now and can go later based on the discussions. > Thanks, > > Ingo