Messages in this thread | | | Date | Thu, 29 Nov 2007 11:30:35 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] sched: cpu accounting controller |
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On Fri, 30 Nov 2007 00:47:37 +0530 Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> wrote:
> On Mon, Nov 12, 2007 at 11:57:03PM -0800, Paul Menage wrote: > > > Regarding your concern about tracking cpu usage in different ways, it > > > could be mitigated if we have cpuacct controller track usage as per > > > information present in a task's sched entity structure > > > (tsk->se.sum_exec_runtime) i.e call cpuacct_charge() from > > > __update_curr() which would accumulate the execution time of the > > > group in a SMP friendly manner (i.e dump it in a per-cpu per-group counter > > > first and then aggregate to a global per-group counter). > > > > That seems more reasonable than the current approach in cpu_acct.c > > Paul, > Sorry about the delay in getting back to this thread. I realized > very recently that cpuacct controller has been removed from Linus's tree > and have attempted to rework it as per our discussions. > > Linus/Ingo, > Commit cfb5285660aad4931b2ebbfa902ea48a37dfffa1 removed a usefull > feature for us, which provided a cpu accounting resource controller. This > feature would be usefull if someone wants to group tasks only for accounting > purpose and doesnt really want to exercise any control over their cpu > consumption. > > The patch below reintroduces the feature. It is based on Paul Menage's > original patch (Commit 62d0df64065e7c135d0002f069444fbdfc64768f), with > these differences: > > - Removed load average information. I felt it needs > more thought (esp to deal with SMP and virtualized platforms) > and can be added for 2.6.25 after more discussions. > - Convert group cpu usage to be nanosecond accurate (as rest > of the cfs stats are) and invoke cpuacct_charge() from > the respective scheduler classes > > The patch also modifies the cpu controller not to provide the same > accounting information. > > ... > > - Make the accounting scalable on SMP systems (perhaps > for 2.6.25)
That sounds like a rather important todo. How bad is it now?
> Index: current/include/linux/cpu_acct.h > =================================================================== > --- /dev/null > +++ current/include/linux/cpu_acct.h > @@ -0,0 +1,14 @@ > + > +#ifndef _LINUX_CPU_ACCT_H > +#define _LINUX_CPU_ACCT_H > + > +#include <linux/cgroup.h> > +#include <asm/cputime.h> > + > +#ifdef CONFIG_CGROUP_CPUACCT > +extern void cpuacct_charge(struct task_struct *, u64 cputime);
^ no "p"
> +#else > +static inline void cpuacct_charge(struct task_struct *p, u64 cputime) {}
^ "p" > +#endif
Personally I think "p" is a dopey name - we tend to standardise on "tsk" for this.
> --- /dev/null > +++ current/kernel/cpu_acct.c > @@ -0,0 +1,103 @@ > +/* > + * kernel/cpu_acct.c - CPU accounting cgroup subsystem > + * > + * Copyright (C) Google Inc, 2006 > + * > + * Developed by Paul Menage (menage@google.com) and Balbir Singh > + * (balbir@in.ibm.com) > + * > + */ > + > +/* > + * Example cgroup subsystem for reporting total CPU usage of tasks in a > + * cgroup. > + */ > + > +#include <linux/module.h> > +#include <linux/cgroup.h> > +#include <linux/fs.h> > +#include <linux/rcupdate.h> > + > +#include <asm/div64.h>
I don't think this inclusion is needed?
> +struct cpuacct { > + struct cgroup_subsys_state css; > + spinlock_t lock; > + /* total time used by this class (in nanoseconds) */ > + u64 time; > +}; > + > +struct cgroup_subsys cpuacct_subsys;
This can be made static.
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