From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: Re: blkback name greater than 16 characters issue Date: Mon, 4 Jan 2016 11:51:16 +0000 Message-ID: <20160104115116.GF9423@citrix.com> References: <20151214164635.GA9191@char.us.oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aG3fV-0004EE-5L for xen-devel@lists.xenproject.org; Mon, 04 Jan 2016 11:51:21 +0000 Content-Disposition: inline In-Reply-To: <20151214164635.GA9191@char.us.oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Konrad Rzeszutek Wilk Cc: wei.liu2@citrix.com, ian.campbell@citrix.com, julien.grall@citrix.com, jbeulich@suse.com, xen-devel@lists.xenproject.org, ian.jackson@citrix.com, roger.pau@citrix.com List-Id: xen-devel@lists.xenproject.org On Mon, Dec 14, 2015 at 11:46:35AM -0500, Konrad Rzeszutek Wilk wrote: > Hey, > > Way back in the past Jan pointed out this issue > http://lists.xenproject.org/archives/html/xen-devel/2015-05/msg03505.html > > which is that the device name is "blkback.." > > for exmaple: blkback.8.xvda, blkback.11.hda > > With the multiqueue block backend we add "-%d" for the queue. > But sadly this is already way past the limit so it gets stripped. > > > Possible solution had been identified by Ian: > http://lists.xenproject.org/archives/html/xen-devel/2015-05/msg03516.html > > " > If you are pressed for space then the "xvd" is probably a bit redundant > in a string which starts blkbk. > > The guest may not even call the device xvdN (iirc BSD has another > prefix) any how, so having blkback say so seems of limited use anyway. > > Since this seems to not include a partition number how does this work in > the split partition scheme? (i.e. one where the guest is given xvda1 and > xvda2 rather than xvda with a partition table) > > [It will be 'blkback.8.xvda1', and 'blkback.11.xvda2'] > > Perhaps something derived from one of the schemes in > http://xenbits.xen.org/docs/unstable/misc/vbd-interface.txt might be a > better fit? > " > > [Inline is my answer] > > My desire is to easily correlate the name of the thread with the > guest config. And that means preserving the 'xvda' or 'hda' or whatever > the user had in mind. > > I believe the domain id is important as well - so we need that. > > Which means we are left with the prefix. Should it be 'blkbk' or > should it be completely eliminated? Meaning we have: > > 8.xvda > 11.hda > > and > 9.xvda-1 > 9.xvda-2 > 32100.xvdfg9-5 > > Or perhaps use 'blk." > > blk.32100.xvdfg9-5 > (exactly 17, so '5' is gone). > > Perhaps in those occassions drop 'blk.' altogether? But I wouldn't want > a special case, so back to: > > 32100.xvdfg9-5 > > ? Thoughts? > > Or > ? Or enlarge TASK_COMM_LEN? :-) Jokes aside, 'git grep blkback' in tools directory doesn't show any reference to "blkback" in code (as I would expect), so there is no risk in breaking tookstack should you change the name. I don't really have a preference whatsoever on this. Wei.