From mboxrd@z Thu Jan 1 00:00:00 1970 From: Serge Hallyn Subject: Re: cpu shielding. Date: Mon, 6 Feb 2012 20:15:27 -0600 Message-ID: <20120207021527.GA17937@sergelap> References: <1328536234.32188.49.camel@foo> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1328536234.32188.49.camel@foo> 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: atp Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org List-Id: containers.vger.kernel.org Quoting atp (Andrew.Phillips-xheW4WVAX9Y@public.gmane.org): > Hello, > > Apologies if I'm about to ask a frequently asked question - I did > check back over the last couple of months. > > Is anyone working on cpu shielding for processes inside a cpu cgroup? > > We would like to run Java in containers, and unfortunately it likes to > know how many processors there are in the system - to initialise thread > pools and such like. > > I was thinking along these lines; > > --- fs/proc/stat.c.orig 2010-05-21 11:32:32.941258466 +0000 > +++ fs/proc/stat.c 2010-05-21 11:40:47.681259133 +0000 > @@ -39,7 +39,9 @@ > getboottime(&boottime); > jif = boottime.tv_sec; > > - for_each_possible_cpu(i) { > +// for_each_possible_cpu(i) { > +// // refer to the visible cpus. > + for_each_cpu_and(i,cpu_possible_mask,(¤t->cpus_allowed)) { > user = cputime64_add(user, kstat_cpu(i).cpustat.user); > nice = cputime64_add(nice, kstat_cpu(i).cpustat.nice); > system = cputime64_add(system, kstat_cpu(i).cpustat.system); > @@ -78,7 +80,10 @@ > (unsigned long long)cputime64_to_clock_t(steal), > (unsigned long long)cputime64_to_clock_t(guest), > (unsigned long long)cputime64_to_clock_t(guest_nice)); > - for_each_online_cpu(i) { > + > +// for_each_online_cpu(i) { > +// // cgroup. > + for_each_cpu_and(i,cpu_online_mask,(¤t->cpus_allowed)) { > > /* Copy values here to work around gcc-2.95.3, gcc-2.96 */ > user = kstat_cpu(i).cpustat.user; > > I'm sure that there are nicer ways of doing this, but Serge Hallyn > suggested a while ago that I post here. Even though it says 2010, the > patch above looks like it will go against 3.2.4 ok. > > Thanks, > Andy I'm afraid I haven't been following recent upstream discussions on this, but there are other people who want proc to show cgroup-limited information. See for instance http://lwn.net/Articles/460310/ . Glauber has also brought this up since then. I'd recommend pinging him. I'm all for /proc showing cgroup-filtered information, unconditionally. -serge