From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 357A82D7387 for ; Tue, 25 Nov 2025 07:48:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764056938; cv=none; b=Yp8EcreBm73Ssp99xONdmefhroZk8RNxntgJxzISNLvA7Z4ksczHhiEKUMNolWtz5pScltB0rAuZ9o/h1wbGWZrmV+KdreW5NijWgc9FomZtCPRy6eoMhBG/4lTT3QJWq6kPzjW3vfEnU8MpLmSJD8Obo+DhYWwebRy5ihs5S1Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764056938; c=relaxed/simple; bh=Yp2OICC+dT3r7A+LJziJy0dfokkbEcEq7u2c/S/UchU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=OWa0AeRHl01JmptwzQuFk9MblR/oTfC/L3iLT5e5rmLnuJXQ3XG1xi/8KeVARkUerADBec1gcV1+cP3AQuDztqRunisyqc92DVtzOc0tIJmJMSa/Yw3PSySUsjmzGgsW603De6FSxpeRJzeJWJ2P/vylHhNi9E7WW95Qe1UiyEE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G6JmKqWL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="G6JmKqWL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90B5DC116D0; Tue, 25 Nov 2025 07:48:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764056937; bh=Yp2OICC+dT3r7A+LJziJy0dfokkbEcEq7u2c/S/UchU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=G6JmKqWLZhFBI9aXUmpm3W4crt2Mkk+UAPHJjw2X20I7G6hICzp3MqkUpkxvHS9fi WO2v2p4c5QnoeiYUHvzzbU09dkQr790hRjZf3/DYHgaaSHuwMLMmcf3cjraZkArKgf 46/2ZNFX4wvXeCTqEwAJ5yf0JqxMe6iEW7GDEjP+6LnDkOEjQ1Qk+ayi/e9x5LnPBy uODOmI9jh0yabgHyffiC4TECqPl+lGoPe0mQt+6f7d/h80ncMPoONHDI8A57B9AYqK sg566nRAq/FeMu+Hw4Yvo+YU0F80FzEIL0CU7TvwNqVfM2dOmFJ6HdlyUToEukL9Ko wVqqbrQE1Ua8w== Message-ID: <0f53d5b8-dbb7-4265-940a-2f2be3d0154d@kernel.org> Date: Tue, 25 Nov 2025 08:48:48 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 00/17] Paravirt CPUs and push task for less vCPU preemption To: Shrikanth Hegde , Greg KH Cc: 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, yury.norov@gmail.com, maddy@linux.ibm.com, srikar@linux.ibm.com, pbonzini@redhat.com, seanjc@google.com, kprateek.nayak@amd.com, vschneid@redhat.com, iii@linux.ibm.com, huschle@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com References: <20251119124449.1149616-1-sshegde@linux.ibm.com> <2025112454-phonics-crept-5b98@gregkh> <4b83b443-baa8-4218-8412-ddfb0dda8ac3@linux.ibm.com> From: "Christophe Leroy (CS GROUP)" Content-Language: fr-FR In-Reply-To: <4b83b443-baa8-4218-8412-ddfb0dda8ac3@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi Shrikanth, Le 25/11/2025 à 03:39, Shrikanth Hegde a écrit : > Hi Greg. > > On 11/24/25 10:35 PM, Greg KH wrote: >> On Wed, Nov 19, 2025 at 06:14:32PM +0530, Shrikanth Hegde wrote: >>> Detailed problem statement and some of the implementation choices were >>> discussed earlier[1]. >>> >>> [1]: https://eur01.safelinks.protection.outlook.com/? >>> url=https%3A%2F%2Flore.kernel.org%2Fall%2F20250910174210.1969750-1- >>> sshegde%40linux.ibm.com%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7Cc7e5a5830fcb4c796d4808de2bcbe09d%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638996351808032890%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=cV8RTPdV3So1GwQ9uVYgUuGxSfxutSezpaNBq6RYn%2FI%3D&reserved=0 >>> >>> This is likely the version which would be used for LPC2025 discussion on >>> this topic. Feel free to provide your suggestion and hoping for a >>> solution >>> that works for different architectures and it's use cases. >>> >>> All the existing alternatives such as cpu hotplug, creating isolated >>> partitions etc break the user affinity. Since number of CPUs to use >>> change >>> depending on the steal time, it is not driven by User. Hence it would be >>> wrong to break the affinity. This series allows if the task is pinned >>> only paravirt CPUs, it will continue running there. >>> >>> Changes compared v3[1]: >> >> There is no "v" for this series :( >> > > I thought about adding v1. > > I made it as PATCH from RFC PATCH since functionally it should > be complete now with arch bits. Since it is v1, I remember usually > people send out without adding v1. after v1 had tags such as v2. > > I will keep v2 for the next series. > But you are listing changes compared to v3, how can it be a v1 ? Shouldn't it be a v4 ? Or in reality a v5 as you already sent a v4 here [1]. [1] https://lore.kernel.org/all/20251119062100.1112520-1-sshegde@linux.ibm.com/ Christophe