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Mon, 15 Dec 2025 09:39:15 -0800 (PST) Date: Mon, 15 Dec 2025 12:39:15 -0500 From: Yury Norov To: Shrikanth Hegde Cc: Ilya Leoshkevich , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, tglx@linutronix.de, maddy@linux.ibm.com, srikar@linux.ibm.com, gregkh@linuxfoundation.org, pbonzini@redhat.com, seanjc@google.com, kprateek.nayak@amd.com, vschneid@redhat.com, huschle@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com, christophe.leroy@csgroup.eu, linux-s390@vger.kernel.org Subject: Re: [PATCH 00/17] Paravirt CPUs and push task for less vCPU preemption Message-ID: References: <20251119124449.1149616-1-sshegde@linux.ibm.com> <4ddbb5a1244cf444f330cc73b7d573f47b02f7eb.camel@linux.ibm.com> <8368868e-48aa-4a90-95d1-1be4de9879e8@linux.ibm.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8368868e-48aa-4a90-95d1-1be4de9879e8@linux.ibm.com> On Fri, Dec 05, 2025 at 11:00:18AM +0530, Shrikanth Hegde wrote: > > > On 12/4/25 6:58 PM, Ilya Leoshkevich wrote: > > On Wed, 2025-11-19 at 18:14 +0530, Shrikanth Hegde wrote: ... > > Others have already commented on the naming, and I would agree that > > "paravirt" is really misleading. I cannot say that the previous "cpu- > > avoid" one was perfect, but it was much better. It was my suggestion to switch names. cpu-avoid is definitely a no-go. Because it doesn't explain anything and only confuses. I suggested 'paravirt' (notice - only suggested) because the patch series is mainly discussing paravirtualized VMs. But now I'm not even sure that the idea of the series is: 1. Applicable only to paravirtualized VMs; and 2. Preemption and rescheduling throttling requires another in-kernel concept other than nohs, isolcpus, cgroups and similar. Shrikanth, can you please clarify the scope of the new feature? Would it be useful for non-paravirtualized VMs, for example? Any other task-cpu bonding problems? On previous rounds you tried to implement the same with cgroups, as far as I understood. Can you discuss that? What exactly can't be done with the existing kernel APIs? Thanks, Yury > > [1] https://github.com/iii-i/linux/commits/iii/poc/cpu-avoid/v3/ > > Will look into it. one thing to to be careful are CPU numbers.