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Date: Fri, 17 Apr 2020 11:11:34 +0800 From: Muchun Song <songmuchun@...edance.com> To: Steven Rostedt <rostedt@...dmis.org> Cc: mingo@...hat.com, Peter Zijlstra <peterz@...radead.org>, juri.lelli@...hat.com, Vincent Guittot <vincent.guittot@...aro.org>, dietmar.eggemann@....com, Benjamin Segall <bsegall@...gle.com>, mgorman@...e.de, mingo@...nel.org, linux-kernel@...r.kernel.org Subject: Re: [External] Re: [PATCH] sched/cpuacct: Fix charge cpuacct.usage_sys incorrently. On Fri, Apr 17, 2020 at 12:01 AM Steven Rostedt <rostedt@...dmis.org> wrote: > > On Thu, 16 Apr 2020 11:35:02 -0400 > Steven Rostedt <rostedt@...dmis.org> wrote: > > > On Thu, 16 Apr 2020 22:18:33 +0800 > > Muchun Song <songmuchun@...edance.com> wrote: > > > > > The user_mode(task_pt_regs(tsk)) always return true for > > > user thread, and false for kernel thread. So it means that > > > the cpuacct.usage_sys is the time that kernel thread uses > > > not the time that thread uses in the kernel mode. We can > > > use get_irq_regs() instead of task_pt_regs() to fix it. > > > > > > Signed-off-by: Muchun Song <songmuchun@...edance.com> > > > --- > > > kernel/sched/cpuacct.c | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c > > > index 6448b0438ffb2..edfc62554648e 100644 > > > --- a/kernel/sched/cpuacct.c > > > +++ b/kernel/sched/cpuacct.c > > > @@ -5,6 +5,7 @@ > > > * Based on the work by Paul Menage (menage@...gle.com) and Balbir Singh > > > * (balbir@...ibm.com). > > > */ > > > +#include <asm/irq_regs.h> > > > #include "sched.h" > > > > > > /* Time spent by the tasks of the CPU accounting group executing in ... */ > > > @@ -339,7 +340,7 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime) > > > { > > > struct cpuacct *ca; > > > int index = CPUACCT_STAT_SYSTEM; > > > - struct pt_regs *regs = task_pt_regs(tsk); > > > + struct pt_regs *regs = get_irq_regs(); > > > > But get_irq_regs() is only available from interrupt context. This will be > > NULL most the time, whereas the original way will have regs existing for > > the task. > > Perhaps you want: > > regs = get_irqs_regs(); > if (!regs) > regs = task_pt_regs(tsk); > > ? Yeah, If regs is NULL, we can get it fall back to task_pt_regs. Does Anyone else have suggestions? > > -- Steve > > > > > > > > > if (regs && user_mode(regs)) > > > index = CPUACCT_STAT_USER; > > -- Yours, Muchun
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