From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id AC471CFD318 for ; Mon, 24 Nov 2025 17:05:11 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4dFXJ61sxPz308l; Tue, 25 Nov 2025 04:05:10 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip="2600:3c04:e001:324:0:1991:8:25" ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1764003910; cv=none; b=hLaKsmCoRmfduD78PFI7ktjTC65gw3Kf7uD2tQK+iT5A7J5G9/xNiBJqeZBwWtVp4KGFIglcEt+27h2vD9zy5jXns81SGyRFbOBPgZ7TKMsT0gZ0Ncv5QZSydKK3NSDL/+jJuK6pSc2AmY9zp+8NYfa+yOuPr0RUx0gY65wpaM8VJBt2Lh3+YcAlwP45M0IbZaX3RA488w4Axh8LMDa9xefwsRjXBK9Wl6oAn+BjHCYA1W4AVJRnhWjTLRjhRY0YDxBUd8sF3CSDCWftNqrqc+Wxjv00VGny+Y9ov6EgYo65ITb8a0DHYEgkmq4bD1vCTnJBnK/TC9aAfOV9YGHOaw== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1764003910; c=relaxed/relaxed; bh=6d1Eh1ili1NP0ctEBSfz61thfSkOLbKMxnLdKQNCoPg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=YKKT3JDePjdeJ2lSUD/0J3pvFBKBD1VPp0G6BDBy2bLvbv0aj1qbkLaGsEYe2EWGkWGpr+uwKUoiDZIPFQEuvL5mrXam6dI+0ftgkEbgkMY23uDu+d5zc5UguQea0G99cXEmjLCkC8l4N1qp4nGhtlhDv4FpXGXztTSrjAgsHvsD2YGoCzUFC7nnQAHGkRQJ3TOa+m4Pmm3nc0/hfM/cym5HuE632/pM94ER/xhyxaTlRfRMnDcRDn+HGO0RGwXgZpMKGD3+ZrF+Q1PjzRbd2mwldr2gDoMFSRg0EUnG6dLdPAgpHQWZUT61myJ0upb+G/kUPvAnV20shVGh6SPBmw== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linuxfoundation.org; dkim=pass (1024-bit key; unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=K+421HU7; dkim-atps=neutral; spf=pass (client-ip=2600:3c04:e001:324:0:1991:8:25; helo=tor.source.kernel.org; envelope-from=gregkh@linuxfoundation.org; receiver=lists.ozlabs.org) smtp.mailfrom=linuxfoundation.org Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=K+421HU7; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linuxfoundation.org (client-ip=2600:3c04:e001:324:0:1991:8:25; helo=tor.source.kernel.org; envelope-from=gregkh@linuxfoundation.org; receiver=lists.ozlabs.org) Received: from tor.source.kernel.org (tor.source.kernel.org [IPv6:2600:3c04:e001:324:0:1991:8:25]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4dFXJ54rDYz305M for ; Tue, 25 Nov 2025 04:05:09 +1100 (AEDT) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 183AB60173; Mon, 24 Nov 2025 17:05:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31DE1C4CEF1; Mon, 24 Nov 2025 17:05:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764003906; bh=D3KrTWBY6jm2x9Hlo2t7wMeEpeX0KvUBsFsMbqIhc2o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=K+421HU7jXKTq/rssClIwxW2gbgjEygTlAxVGxzWNzfE3uBv2/vh8nYpCKJqPhUif h+k5xJaRSeYq0Y4yt0OaMMTDiCTzySK7AC21uyjvR76Ts4TRrDiam7ViR0Uwuwop/o 1mlMGnNYVUN1lu29pzRqmRmjIhLbxBGvuWI8legg= Date: Mon, 24 Nov 2025 18:05:04 +0100 From: Greg KH To: Shrikanth Hegde 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, christophe.leroy@csgroup.eu Subject: Re: [PATCH 00/17] Paravirt CPUs and push task for less vCPU preemption Message-ID: <2025112454-phonics-crept-5b98@gregkh> References: <20251119124449.1149616-1-sshegde@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: <20251119124449.1149616-1-sshegde@linux.ibm.com> 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://lore.kernel.org/all/20250910174210.1969750-1-sshegde@linux.ibm.com/ > > 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 :(