From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: cgroup: status-quo and userland efforts Date: Tue, 9 Apr 2013 12:11:45 -0700 Message-ID: <20130409191145.GI6186@mtj.dyndns.org> References: <20130406012159.GA17159@mtj.dyndns.org> <5162CA21.4060108@parallels.com> <51635371.7070104@redhat.com> 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=x-received:sender:date:from:to:cc:subject:message-id:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; bh=n9Uelgt4VxD9wzBunUnG5LZcJSTL8UDlCxgZXTg5us4=; b=auKTahTYhz9fVLOKjZBRcHjCS6jjlhM0YYKjj2pj2BDK2IpPuqoKYSYOOSt6ERu2t0 9XsYEa6SgR2amfah+7xCLhWDKvEjHWsKPoNNs1ThbKIBqRLMRuS2icM1ICAERBnCg7hE Caa9SZP5POqhmdAUe9LZ527HxsY4yqKdU+MKktA9nhj4nUZocf1TKLU+4xU2jDqUkWM0 SxIDeHWdOPQD9MfbPPE5Ou7aGPWhG3C8colnt8+tNtCoakkOJKYiNKufSWhJnvYoU9sa ppqiEohXXn2KW26iUoInwoyK52r4PeDFczWoLzC3oh0Bt2c2rJwEd7wNitq1ojN4a+pn fh3g== Content-Disposition: inline In-Reply-To: <51635371.7070104-H+wXaHxf7aLQT0dZR+AlfA@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: Lennart Poettering Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Kay Sievers , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jpoimboe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dhaval.giani-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, workman-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org Hello, On Tue, Apr 09, 2013 at 01:32:01AM +0200, Lennart Poettering wrote: > The other big thing we want from the systemd side is saner > notifications when cgroups run empty. i.e. currently we don't get > these at all in containers (since the agent can be only installed > once, for the host). And the way we get this is awful, via > kernel-spawned processes. I am looking for a way how I can establish > a watch on a certain subtree (not just one directory) and get simple > notifications in a race-free whenever a cgroup runs empty. Oh yeah, it's horrifying. There was something going on a while ago but I couldn't get hold of Eric Paris. We probably should resurrect that patch. As for delegating to namespaces, I'm not exactly sure what to do. At least for now, it could be an acceptable trade-off to delegate the subdirectory with some limits on the number of cgroups / depth of hierarchy / whatever. That said, I'm not really fond of the idea. It isn't likely to work seamlessly. The root cgroup is special anyway and I don't really like the idea of putting NS related stuff directly into cgroupfs. Thanks. -- tejun