From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=193.142.43.55 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793777834; b=QWqhnnsJpL4niscPw1t2fBLErfI3MnePMol5rZUwJbit+XeET7XSwG+i3cT9rDLkqDJ5 J5teTW9WAERy6cdbt4l7/XG9mUz6x+fKCrzhNVh1cs9xRg/H+m8dIg7lJiled1xAwxHHh NeQ4SZ0IHs4VPGdMmP/Sp63iDZqtMkjhCPJrAPFZG3u4IwmBOP6H6Tm2dhbl9stjAWQRh 9FfCM5n0nEtUBE57M2kmsYvsLLTc9Kn+FdnD9DqLYUAosArVfWgYy0BBDKYC6kl8nQUxK JdqoXjAfb0Quhqgf7bmFUlNApVkUIT+SR8AA/+yvhXrlnUpymyjX608+T/MCmjkeslw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793777834; h=DMARC-Filter:Date:DKIM-Signature:DKIM-Signature:From:To:Cc:Subject: Message-ID:References:MIME-Version:Content-Type:Content-Disposition: In-Reply-To; bh=a5bZ2lIZiEkVoZLtojIf8IXJVOMItCBOSHoLzBHJXI8=; b=fv0QScjIFanJwOaxmwtFjfQaycLLpKMTyqOd5oJ7oQ1vWO1aEhnW2PLarrItnT5QG/a7 YSfFj/1wcSCsbDd1dbtOsDJe/yMWK6mVzKxMMZQtS1v8dxNh7X9AGATwYJU3qACDICB7F l3jnHboYZjkNVxlPuxQFce9o7Wd+njvHu1YI/U40+v9qmeA7BAJ/vtLYO3Vk2VR/70Nkv 5Cs2dhjz6diagBLWKBF6ehbuhcusyyMdMbOi/efagFw+nhmENDj14X/JktVZBVjyEWPKl XNyl/t+n+kW7kIrKgHfAoAAxEhXhZ7Cmc2IRrVA50q7J+YhZSg9L5zfW3uh9yhigO/w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=BgO1Xsj6; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=5fLGN7uT; arc=none smtp.remote-ip=193.142.43.55 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 60281606A332; Wed, 4 Nov 2026 07:37:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 60281606A332 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=BgO1Xsj6; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=5fLGN7uT Date: Wed, 4 Nov 2026 08:37:10 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1793777832; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=a5bZ2lIZiEkVoZLtojIf8IXJVOMItCBOSHoLzBHJXI8=; b=BgO1Xsj6UVvItDbkKR7DF62E98m3dvPI+mk5pF8NY4o+sygzv3liHbPn/Ust4nPxeVf55J 07JVZVihODGmN2UvZPK478aAbJJV2hgZY7BVd6GPmxVgpfWddXeaX4k3RuK6/ahu6l2cdM XGG5g92pz3A+SwsKc6iqsI9Eu2rScoYLJ5vyQ93H/GNpNb02pa3Ue3lohqDxmS37ho3Ty2 dEt9LwD7oHSNcVVDAfkH7sgkRvfDZsUAayYsjaQMTqSablNp7Vl2R3MoopS2CoTeNz5tY3 DEZbKWa6m+zH5nBZitr0ArTPZjbVItYaYivT4MbN1FQb7HgbWNqoSgpFPCZdMA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1793777832; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=a5bZ2lIZiEkVoZLtojIf8IXJVOMItCBOSHoLzBHJXI8=; b=5fLGN7uTtzDfUk8Ypn+enBJObhEK8ZoIGSIFUdB73ea7ijV9e5PLm+s0K8a1alIwP+FdsS FHQOw+pSO+wEriAQ== From: Sebastian Andrzej Siewior To: Christoph Hellwig Cc: Daniel Wagner , Keith Busch , Jens Axboe , Sagi Grimberg , Ming Lei , Surabhi Gogte , Hannes Reinecke , Nilay Shroff , Frederic Weisbecker , Aaron Tomlin , Maurizio Lombardi , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] blk-mq: use a housekeeping CPU for passthrough requests on isolated hctxs Message-ID: <20261104073710.kTUsM3JV@linutronix.de> References: <20261103-nvme-fabrics-isolcpu-v2-1-95ec70d58254@suse.de> <20261103163748.qDpZjKj8@linutronix.de> <20261104071703.GC28939@lst.de> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20261104071703.GC28939@lst.de> On 2026-11-04 08:17:03 [+0100], Christoph Hellwig wrote: > On Tue, Nov 03, 2026 at 05:37:48PM +0100, Sebastian Andrzej Siewior wrote: > > What about > > guard(rcu); > > for_each_cpu_and(cpu, cpu_online_mask, housekeeping_cpumask(HK_TYPE_MANAGED_IRQ)) { > > if (!cpu_is_isolated(cpu) > > break; > > } > > > > this ends up with one less function call ;) > > Please avoid this completely unreadable and unaditable guard crap. If you/ block prefers to avoid guard() then fine. I usually get punched the other way around. > How is anyone supposed to understand that above mess? I can show you code where you start crying. Anyway. My main selling point was for_each_cpu_and(). Sebastian