From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 02BB921107474 for ; Sat, 1 Sep 2018 01:25:09 -0700 (PDT) Date: Sat, 1 Sep 2018 10:28:12 +0200 From: Christoph Hellwig Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests Message-ID: <20180901082812.GB670@lst.de> References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Jens Axboe Cc: Alex Williamson , linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, =?iso-8859-1?B?Suly9G1l?= Glisse , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , Benjamin Herrenschmidt , Bjorn Helgaas , Max Gurtovoy , Christoph Hellwig List-ID: On Thu, Aug 30, 2018 at 01:11:18PM -0600, Jens Axboe wrote: > I think this belongs in the caller - both the validity check, and > passing in NOMERGE for this type of request. I don't want to impose > this overhead on everything, for a pretty niche case. It is just a single branch, which will be predicted as not taken for non-P2P users. The benefit is that we get proper error checking by doing it in the block code. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Sat, 1 Sep 2018 10:28:12 +0200 From: Christoph Hellwig To: Jens Axboe Cc: Logan Gunthorpe , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, linux-nvdimm@lists.01.org, linux-block@vger.kernel.org, Stephen Bates , Christoph Hellwig , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Jason Gunthorpe , Max Gurtovoy , Dan Williams , =?iso-8859-1?B?Suly9G1l?= Glisse , Benjamin Herrenschmidt , Alex Williamson , Christian =?iso-8859-1?Q?K=F6nig?= Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests Message-ID: <20180901082812.GB670@lst.de> References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: List-ID: On Thu, Aug 30, 2018 at 01:11:18PM -0600, Jens Axboe wrote: > I think this belongs in the caller - both the validity check, and > passing in NOMERGE for this type of request. I don't want to impose > this overhead on everything, for a pretty niche case. It is just a single branch, which will be predicted as not taken for non-P2P users. The benefit is that we get proper error checking by doing it in the block code. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests Date: Sat, 1 Sep 2018 10:28:12 +0200 Message-ID: <20180901082812.GB670@lst.de> References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" To: Jens Axboe Cc: Alex Williamson , linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nvme-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, =?iso-8859-1?B?Suly9G1l?= Glisse , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , Benjamin Herrenschmidt , Bjorn Helgaas , Max Gurtovoy , Christoph Hellwig List-Id: linux-rdma@vger.kernel.org On Thu, Aug 30, 2018 at 01:11:18PM -0600, Jens Axboe wrote: > I think this belongs in the caller - both the validity check, and > passing in NOMERGE for this type of request. I don't want to impose > this overhead on everything, for a pretty niche case. It is just a single branch, which will be predicted as not taken for non-P2P users. The benefit is that we get proper error checking by doing it in the block code. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Date: Sat, 1 Sep 2018 10:28:12 +0200 From: Christoph Hellwig To: Jens Axboe Subject: Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests Message-ID: <20180901082812.GB670@lst.de> References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> MIME-Version: 1.0 In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Keith Busch , Alex Williamson , Sagi Grimberg , linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Stephen Bates , linux-block@vger.kernel.org, =?iso-8859-1?B?Suly9G1l?= Glisse , Jason Gunthorpe , Christian =?iso-8859-1?Q?K=F6nig?= , Benjamin Herrenschmidt , Bjorn Helgaas , Max Gurtovoy , Dan Williams , Logan Gunthorpe , Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+bjorn=helgaas.com@lists.infradead.org List-ID: On Thu, Aug 30, 2018 at 01:11:18PM -0600, Jens Axboe wrote: > I think this belongs in the caller - both the validity check, and > passing in NOMERGE for this type of request. I don't want to impose > this overhead on everything, for a pretty niche case. It is just a single branch, which will be predicted as not taken for non-P2P users. The benefit is that we get proper error checking by doing it in the block code. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme From mboxrd@z Thu Jan 1 00:00:00 1970 From: hch@lst.de (Christoph Hellwig) Date: Sat, 1 Sep 2018 10:28:12 +0200 Subject: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests In-Reply-To: References: <20180830185352.3369-1-logang@deltatee.com> <20180830185352.3369-8-logang@deltatee.com> Message-ID: <20180901082812.GB670@lst.de> On Thu, Aug 30, 2018@01:11:18PM -0600, Jens Axboe wrote: > I think this belongs in the caller - both the validity check, and > passing in NOMERGE for this type of request. I don't want to impose > this overhead on everything, for a pretty niche case. It is just a single branch, which will be predicted as not taken for non-P2P users. The benefit is that we get proper error checking by doing it in the block code.