From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 1/2] Convert target drivers to use sbitmap Date: Tue, 15 May 2018 10:20:37 -0600 Message-ID: <6ab7d206-ba46-6b1e-5210-4894ec4dc553__35360.1573304788$1526401145$gmane$org@kernel.dk> References: <20180515160043.27044-1-willy@infradead.org> <20180515160043.27044-2-willy@infradead.org> <3a56027b-47bc-dcb8-a465-3670031572f1@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <3a56027b-47bc-dcb8-a465-3670031572f1@kernel.dk> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Matthew Wilcox , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-usb@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, Juergen Gross , qla2xxx-upstream@qlogic.com, Kent Overstreet Cc: Matthew Wilcox List-Id: virtualization@lists.linuxfoundation.org On 5/15/18 10:11 AM, Jens Axboe wrote: > On 5/15/18 10:00 AM, Matthew Wilcox wrote: >> From: Matthew Wilcox >> >> The sbitmap and the percpu_ida perform essentially the same task, >> allocating tags for commands. Since the sbitmap is more used than >> the percpu_ida, convert the percpu_ida users to the sbitmap API. > > It should also be the same performance as percpu_ida in light use, and > performs much better at > 50% utilization of the tag space. I think > that's better justification than "more used than". Had to search long and hard for the perf numbers I did for percpu_ida on higher utilization, but here it is: https://lkml.org/lkml/2014/4/22/553 -- Jens Axboe