From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: Re: [PATCH 4/7] dm mpath: remove process_queued_ios() Date: Tue, 11 Feb 2014 10:55:53 -0500 Message-ID: <20140211155552.GB27812@redhat.com> References: <1391511280-29325-1-git-send-email-hare@suse.de> <1391511280-29325-5-git-send-email-hare@suse.de> <11AF7C027C4C02408624617A498607840105F76A@BPXM12GP.gisp.nec.co.jp> <52F0CF91.60302@suse.de> <20140210133046.GA19209@redhat.com> <52F9F18A.9000309@suse.de> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <52F9F18A.9000309@suse.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Hannes Reinecke Cc: Junichi Nomura , "dm-devel@redhat.com" , Alasdair Kergon List-Id: dm-devel.ids On Tue, Feb 11 2014 at 4:46am -0500, Hannes Reinecke wrote: > On 02/10/2014 02:30 PM, Mike Snitzer wrote: > > > > Just to verify, this seems to be the only outstanding question for this > > patchset? > > > > What value are you using for HZ? If this portion of the change does > > turn out to be meaningul: Rather than tieing to HZ should we just use an > > explicitly non-zero value for __pg_init_all_paths()'s @min_delay? > > > The actual amount here is irrelevant, as long as it's non-zero. > It's just there to force execution of the work item off the current > thread. I'm aware we just need a non-zero value. My concern, as originally raised by Junichi in an earlier reply when you had it as HZ/50, is that the value could be 0 if HZ is really small. While unlikely I see no point allowing the variable nature of HZ compromise passing a non-zero value here. Best to just be explicit by passing 1 or something. All said, the question of why this is actually needed remains. I trust you're working on answering that via reproducer (by not forcing the use of workqueue context)?