Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755954AbaFKRJ0 (ORCPT ); Wed, 11 Jun 2014 13:09:26 -0400 Received: from mga02.intel.com ([134.134.136.20]:38501 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751220AbaFKRJZ (ORCPT ); Wed, 11 Jun 2014 13:09:25 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,459,1400050800"; d="scan'208";a="526938857" Date: Wed, 11 Jun 2014 13:09:17 -0400 From: Matthew Wilcox To: Jens Axboe Cc: Keith Busch , Matias =?iso-8859-1?Q?Bj=F8rling?= , "sbradshaw@micron.com" , "tom.leiming@gmail.com" , "hch@infradead.org" , "linux-kernel@vger.kernel.org" , "linux-nvme@lists.infradead.org" Subject: Re: [PATCH v7] NVMe: conversion to blk-mq Message-ID: <20140611170917.GA12025@linux.intel.com> References: <1402392038-5268-2-git-send-email-m@bjorling.me> <5397636F.9050209@fb.com> <5397753B.2020009@fb.com> <20140610213333.GA10055@linux.intel.com> <539889DC.7090704@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <539889DC.7090704@fb.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 11, 2014 at 10:54:52AM -0600, Jens Axboe wrote: > OK, so essentially any single request must be a virtually contig piece > of memory. Is there any size limitations to how big this contig segment > can be? The maximum size of an I/O is 65536 sectors. So on a 512-byte sector device, that's 32MB, but on a 4k sector size device, that's 128MB. > I think this is unique requirement, at least I haven't seen other pieces > of hardware have it. But it would be pretty trivial to add a setting to > limit merges based on virtually contig, similarly to what is done for > number of physical segments. I think there might be an FCoE device with that requirement too. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/