Date: Tue, 16 Aug 2011 09:25:20 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Yuri <yuri@rawbw.com>, Alexander Best <arundel@freebsd.org> Subject: Re: top(1) loses process user time count when threads end Message-ID: <201108160925.20568.jhb@freebsd.org> In-Reply-To: <4E3D808F.1030101@rawbw.com> References: <4E3CC033.6070604@rawbw.com> <20110806091127.GA39951@freebsd.org> <4E3D808F.1030101@rawbw.com>
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On Saturday, August 06, 2011 1:57:35 pm Yuri wrote:
> On 08/06/2011 02:11, Alexander Best wrote:
> > On Fri Aug 5 11, Yuri wrote:
> >> I have the process that first runs in 3 threads but later two active
> >> threads exit.
> >>
> >> top(1) shows this moment this way (1 sec intervals):
> >> 30833 yuri 3 76 0 4729M 4225M nanslp 4 0:32 88.62% app
> >> 30833 yuri 3 76 0 4729M 4225M nanslp 6 0:34 90.92% app
> >> 30833 yuri 1 96 0 4729M 4225M CPU1 1 0:03 1.17% app
> >> 30833 yuri 1 98 0 4729M 4226M CPU1 1 0:04 12.89% app
> >>
> >> Process time goes down: 0:34 -> 0:03. Also WCPU goes down 90.92% ->
> >> 1.17% even though this process is CPU bound and does intense things
> >> right after threads exit.
> >>
> >> getrusage(2) though, called in the process, shows the correct user time.
> >>
> >> I think this is the major bug in the process time accounting.
> > could you check, whether kern/128177 or kern/140892 describe your situation?
>
> I have ULE scheduler. kern/128177 talks about single thread with ULE
> scheduler, and my issue is with threads. So I am not sure if it is
> related. There have been no motion on kern/128177 since Feb 9, 2009.
> kern/140892 is probably the same as mine.
>
> In any case, both these PRs have to be fixed since they are very user
> visible, not just some obscure issues.
You can try this perhaps:
Index: kern/kern_thread.c
===================================================================
--- kern/kern_thread.c (revision 224879)
+++ kern/kern_thread.c (working copy)
@@ -381,7 +381,7 @@
void
thread_exit(void)
{
- uint64_t new_switchtime;
+ uint64_t runtime, new_switchtime;
struct thread *td;
struct thread *td2;
struct proc *p;
@@ -410,15 +410,6 @@
*/
cpu_thread_exit(td); /* XXXSMP */
- /* Do the same timestamp bookkeeping that mi_switch() would do. */
- new_switchtime = cpu_ticks();
- p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime));
- PCPU_SET(switchtime, new_switchtime);
- PCPU_SET(switchticks, ticks);
- PCPU_INC(cnt.v_swtch);
- /* Save our resource usage in our process. */
- td->td_ru.ru_nvcsw++;
- rucollect(&p->p_ru, &td->td_ru);
/*
* The last thread is left attached to the process
* So that the whole bundle gets recycled. Skip
@@ -467,7 +458,21 @@
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
#endif
PROC_UNLOCK(p);
+
+ /* Do the same timestamp bookkeeping that mi_switch() would do. */
+ new_switchtime = cpu_ticks();
+ runtime = new_switchtime - PCPU_GET(switchtime);
+ td->td_runtime += runtime;
+ td->td_incruntime += runtime;
+ PCPU_SET(switchtime, new_switchtime);
+ PCPU_SET(switchticks, ticks);
+ PCPU_INC(cnt.v_swtch);
+
+ /* Save our resource usage in our process. */
+ td->td_ru.ru_nvcsw++;
ruxagg(p, td);
+ rucollect(&p->p_ru, &td->td_ru);
+
thread_lock(td);
PROC_SUNLOCK(p);
td->td_state = TDS_INACTIVE;
--
John Baldwin
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