From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: remove a few uses of ->queuedata Date: Sat, 9 May 2020 10:23:52 +0200 Message-ID: <20200509082352.GB21834@lst.de> References: <20200508161517.252308-1-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-m68k-owner@vger.kernel.org To: Dan Williams Cc: Christoph Hellwig , Jens Axboe , Jim Paris , Geoff Levand , Joshua Morris , Philip Kelleher , Minchan Kim , Nitin Gupta , Sergey Senozhatsky , linux-m68k@lists.linux-m68k.org, Linux Kernel Mailing List , linux-xtensa@linux-xtensa.org, drbd-dev@lists.linbit.com, linux-block@vger.kernel.org, linuxppc-dev , linux-bcache@vger.kernel.org, linux-raid , linux-nvdimm List-Id: linux-raid.ids On Fri, May 08, 2020 at 11:04:45AM -0700, Dan Williams wrote: > On Fri, May 8, 2020 at 9:16 AM Christoph Hellwig wrote: > > > > Hi all, > > > > various bio based drivers use queue->queuedata despite already having > > set up disk->private_data, which can be used just as easily. This > > series cleans them up to only use a single private data pointer. > > ...but isn't the queue pretty much guaranteed to be cache hot and the > gendisk cache cold? I'm not immediately seeing what else needs the > gendisk in the I/O path. Is there another motivation I'm missing? ->private_data is right next to the ->queue pointer, pat0 and part_tbl which are all used in the I/O submission path (generic_make_request / generic_make_request_checks). This is mostly a prep cleanup patch to also remove the pointless queue argument from ->make_request - then ->queue is an extra dereference and extra churn.