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 878A91DE4CD; Sat, 11 Oct 2025 10:00:21 +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=1760176821; cv=none; b=itGDQDfws2J4GnCp/fbQ3cAxQHpCJnfokR9gLfyz0sESxMXOOz5T5ZqfKyzpaA27KhKYVekuMLBtM/nD5s48/bRjtvMVH37kAUNqxQYHAGkOtCdeYvCNhChLNqd8UAhV7qwX0OsVRhQ5iCFSvv2q7NeRv1uXbCnWqxCROKCtUpc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760176821; c=relaxed/simple; bh=7yk3MyybYlBVgFNRCla3ShEZ9hQTXp85epGyYGmllnE=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=OnxAknfhfjZD25kYW/Sx8KV15QnYVyH/xt7nFu6oxqPx7cJ5HG8McKA1yECKrKmsAR5mfEEixMV4VtpeID/pP8G04qIUu1BsCRtR6LxtsY5ULDQ7FOO9VV0ElVrY5YCgKIllQVprMKSJtUF/Ui8up7XTrkfwwvrtNpg6bbcEWPg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ipWja8p6; 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="ipWja8p6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 07757C4CEF4; Sat, 11 Oct 2025 10:00:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760176821; bh=7yk3MyybYlBVgFNRCla3ShEZ9hQTXp85epGyYGmllnE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ipWja8p6NiPSUbYJhlW2Sa3QetWXS8an+AnAX6jaIAiL6o8yPrCeARTxCT73z7Ill 8FBYVVlvvp3/1ja1SR1A1BmoeevXImnndsTQie6tS15RU3qgGrYt9Bm7qqrtBKw2Mo DAZxK3NbpaLI/zdDVmatyexWWCozkr/ZzzHaE4lhflhkkeulsLgVfOjRnQN5I1mXvF SptpvrMb1YvBj56OxmBKxXjMZd00DX1/8l44TqwmCpGPvF9ltz32/LB1jfnXDIQfJD geopXXVCzxhBd6BWlfknTWZlqnUfC5DJ/6sTybJcSOruLlbdaqnOsKD5pUyXAgEUud hu7d1704Oby6g== Received: from sofa.misterjones.org ([185.219.108.64] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1v7WOg-0000000D7RR-38KY; Sat, 11 Oct 2025 10:00:18 +0000 Date: Sat, 11 Oct 2025 11:00:11 +0100 Message-ID: <87sefpoj10.wl-maz@kernel.org> From: Marc Zyngier To: Thierry Reding Cc: Thomas Gleixner , linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: IRQ thread timeouts and affinity In-Reply-To: References: <86qzvcxi3j.wl-maz@kernel.org> <86o6qgxayt.wl-maz@kernel.org> <86ms60x7w7.wl-maz@kernel.org> <86bjmeyh5m.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: thierry.reding@gmail.com, tglx@linutronix.de, linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Fri, 10 Oct 2025 16:03:01 +0100, Thierry Reding wrote: > > On Fri, Oct 10, 2025 at 03:18:13PM +0100, Marc Zyngier wrote: > > > > CPU hotplug is the main area of concern, and I'm pretty sure it breaks > > this distribution mechanism (or the other way around). Another thing > > is that if firmware isn't aware that 1:N interrupts can (or should) > > wake-up a CPU from sleep, bad things will happen. Given that nobody > > uses 1:N, you can bet that any bit of privileged SW (TF-A, > > hypervisors) is likely to be buggy (I've already spotted bugs in KVM > > around this). > > Okay, I can find out if CPU hotplug is a common use-case on these > devices, or if we can run some tests with that. It's not so much whether CPU hotplug is of any use to your particular box, but whether this has any detrimental impact on *any* machine doing CPU hotplug. To be clear, this stuff doesn't go in if something breaks, no matter how small. M. -- Without deviation from the norm, progress is not possible.