From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH RFC - TAKE TWO - 00/12] New version of the BFQ I/O Scheduler Date: Wed, 4 Jun 2014 10:58:29 -0400 Message-ID: <20140604145829.GF5004@htj.dyndns.org> References: <538C8A47.1050502@kernel.dk> <20140602172454.GA8912@htj.dyndns.org> <538CB515.3090700@kernel.dk> <20140602174250.GC8912@htj.dyndns.org> <538CB87C.7030600@kernel.dk> <20140602185138.GD8912@htj.dyndns.org> <20140602205713.GB8357@kernel.dk> <20140604143136.GA1920@infradead.org> <20140604145053.GE5004@htj.dyndns.org> <20140604145330.GA2955@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=6Ge2Uvlwe4tEvJ3eNZqR3jJcqg2MpRPLQk3RqM2rV9g=; b=Deq+9SakJGDCtY7e3UEpMK6BMuc5qbVad4pzJObBrQICF1s0wDWZy2dUMWEr2XFD8m /C0taSRUZ0W8COTXDjbvYge0+gZkpBlYHEncrtepUfjldRDVZ1xY57O1fm86IUZO+8I2 1NrgmW7cfhH7PFg4Zzeyr1eZtxnOhILq+knY4cJuLMhjhHN6KDmAS5K4VlgrXlSWdrpr jOGfW5gI4y6paD9jOPgZgMTC6ta1lrykwpzCASaXbuIhSAcZo2iBy0ScZ4eFc6TchhX1 +TuzpvJ/rJUhtVIZi9c726YcgW+kBb5FTJKJkdn+rL/SUqjdvFZ4tLnEcZ9QDZmHCtmC RgJw== Content-Disposition: inline In-Reply-To: <20140604145330.GA2955-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Christoph Hellwig Cc: Jens Axboe , Paolo Valente , containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Fabio Checconi , Arianna Avanzini , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Paolo Valente On Wed, Jun 04, 2014 at 07:53:30AM -0700, Christoph Hellwig wrote: > On Wed, Jun 04, 2014 at 10:50:53AM -0400, Tejun Heo wrote: > > Hmmm... the biggest thing is ioscheds. They heavily rely on being > > strongly synchronized and are pretty important for rotating rusts. > > Maybe they can be made to work with blk-mq by forcing single queue or > > something but do we wnat that? > > Jens is planning to add an (optional) I/O scheduler to blk-mq, and > that is indeed required for proper disk support. I don't think there > even is a need to limit it to a single queue technically, although > devices that support multiple queues are unlikely to need I/O > scheduling. I think what Jens is planning is something really minimal. Things like [cb]fq heavily depend on the old block infrastructure. I don't know. Maybe they can be merged in time but I'm not quite sure we'd have enough pressure to actually do that. Host-granular switching should be good enough, I guess. Thanks. -- tejun