From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 A07A518EA1 for ; Fri, 10 May 2024 23:50:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715385040; cv=none; b=KHv87wsDgdZyu7pxeGWPcMrUbjaZgp4V9CBBMOZC2tfgq5sqAe04ohuU8mw2sLPaVEM+4jTW00ailVd97JRQuOLfQqDLnIhbo624oiEGzrCqODlsOwJ3eu0Y9DpOnk/YxezXdj98LUkqD4ipzNi4ysiwiMsceuhbLulWmmsT6xo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715385040; c=relaxed/simple; bh=y5z+M1lyyj10VjOQtNfEmMdhZM6sT9TSdZZeuuyU1Zg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=G8T3I6i/nO0Fa7paBBKPufjyV5nt8W2P01NaGto4g+EFXPLclPP97VhdX0yBqu18IdVEvS255gtQvbx6V24N7e5Mx2pICklGAeeCWCxdv+zT0MbJCQL6mimfkUZjqz6n7g8c69Nt26/8pWZ4G59sjKJi28TTHIO3ufYxtTItgso= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=aMC5Ccu3; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aMC5Ccu3" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1715385037; 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=m0dHDeJXZCALlp2ufSH87EqN0Fr/YawjQbxw3fUy5tg=; b=aMC5Ccu3Vo+w79towc9HXeU8COIVTgtQeRCaF6zxCW6E7quNwMnv+y0YgHKMIoSgl/B1s0 55Bt30gNXx12HxOfooSxPKfTojxZmQSi8ntB95CFN0fsilM94x0eFil1WBqDYlge/JBlbp /lZlfJxEZ++Ra6zrYLHEe0k0cOTrs8Q= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-658-sE9Mt34nMKKddJMPk9c91g-1; Fri, 10 May 2024 19:50:34 -0400 X-MC-Unique: sE9Mt34nMKKddJMPk9c91g-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id DB3CD8030A5; Fri, 10 May 2024 23:50:33 +0000 (UTC) Received: from fedora (unknown [10.72.116.15]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7193344E3AFE; Fri, 10 May 2024 23:50:30 +0000 (UTC) Date: Sat, 11 May 2024 07:50:21 +0800 From: Ming Lei To: Keith Busch Cc: Christoph Hellwig , Keith Busch , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de Subject: Re: [PATCH 2/2] nvme-pci: allow unmanaged interrupts Message-ID: References: <20240510141459.3207725-1-kbusch@meta.com> <20240510141459.3207725-2-kbusch@meta.com> <20240510151047.GA10486@lst.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 On Fri, May 10, 2024 at 10:20:02AM -0600, Keith Busch wrote: > On Fri, May 10, 2024 at 05:10:47PM +0200, Christoph Hellwig wrote: > > On Fri, May 10, 2024 at 07:14:59AM -0700, Keith Busch wrote: > > > From: Keith Busch > > > > > > Some people _really_ want to control their interrupt affinity. > > > > So let them argue why. I'd rather have a really, really, really > > good argument for this crap, and I'd like to hear it from the horses > > mouth. > > It's just prioritizing predictable user task scheduling for a subset of > CPUs instead of having consistently better storage performance. > > We already have "isolcpus=managed_irq," parameter to prevent managed > interrupts from running on a subset of CPUs, so the use case is already > kind of supported. The problem with that parameter is it is a no-op if > the starting affinity spread contains only isolated CPUs. Can you explain a bit why it is a no-op? If only isolated CPUs are spread on one queue, there will be no IO originated from these isolated CPUs, that is exactly what the isolation needs. Thanks, Ming