cpu shielding.

[atp <Andrew.Phillips@xxxxxxxx>]

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,(&current->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,(&current->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

-- 
Andrew Phillips
Head of Systems

Direct: +44 (0)203 192 2509
Mobile: +44 (0)7595 242 900

LMAX, Yellow Building, 1A Nicholas Road,  London, W11 4AN



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