From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 1/3] block: Add iocontext priority to request Date: Tue, 4 Oct 2016 16:52:27 -0400 Message-ID: <20161004205227.GL4205@htj.duckdns.org> References: <1475000096-6148-1-git-send-email-adam.manzanares@hgst.com> <1475000096-6148-2-git-send-email-adam.manzanares@hgst.com> <20160929084059.GB11087@mtj.duckdns.org> <20160930160216.GA13637@hgst.com> <20161002085321.GA13648@mtj.duckdns.org> <20161004154917.GA4764@hgst.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20161004154917.GA4764@hgst.com> Sender: linux-block-owner@vger.kernel.org To: Adam Manzanares Cc: axboe@kernel.dk, linux-block@vger.kernel.org, linux-ide@vger.kernel.org List-Id: linux-ide@vger.kernel.org Hello, Adam. On Tue, Oct 04, 2016 at 08:49:18AM -0700, Adam Manzanares wrote: > > I wonder whether the right thing to do is adding bio->bi_ioprio which > > is initialized on bio submission and carried through req->ioprio. > > I looked around and thought about this and I'm not sure if this will help. > I dug into the bio submission code and I thought generic_make_request was > the best place to save the ioprio information. This is quite close in > the call stack to init_request_from bio. Bcache sets the bio priority before > the submission, so we would have to check to see if the bio priority was > valid on bio submission leaving us with the same problem. Leaving the > priority in the upper bits of bio->bi_rw is fine with me. It may help to > have the bio->bi_ioprio for clarity, but I think we will still face the > issue of having to check if this value is set when we submit the bio or > init the request so I'm leaning towards leaving it as is. I see. Thanks for looking into it. It's icky that we don't have a clear path of propagating ioprio but let's save that for another day. -- tejun