Date: Sun, 11 May 2003 11:44:28 -0400 From: Don Bowman <don@sandvine.com> To: 'Bruce Evans' <bde@zeta.org.au>, Don Bowman <don@sandvine.com> Cc: freebsd-net@freebsd.org Subject: RE: polling(4) and idle time/cpu usage percentages Message-ID: <FE045D4D9F7AED4CBFF1B3B813C8533701B3660D@mail.sandvine.com>
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From: Bruce Evans [mailto:bde@zeta.org.au]
> On Sat, 10 May 2003, Don Bowman wrote:
>
> [accounting for the details of idle time]
>
> > > The former. It's hard for it to work better without
> wasting too many
> > > cycles for the accounting. In RELENG_4, everything done
> in the "idle"
> > > loop is counted as idle time using the single counter
> > > cp_time[CP_IDLE].
> > > This is very efficient.
> >
> > I tried this on my system, but I still end up with 0 system time.
>
> Did you try my hack?
I tried the hack, as below. The other thing that makes idle
wildly inaccurate is the symmetric multi-threading on the xeon
(aka hyperthreading).
Index: kern_clock.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/kern_clock.c,v
retrieving revision 1.105.2.9.1000.2
diff -U3 -r1.105.2.9.1000.2 kern_clock.c
--- kern_clock.c 13 Feb 2003 23:05:58 -0000 1.105.2.9.1000.2
+++ kern_clock.c 10 May 2003 23:41:47 -0000
@@ -68,6 +68,7 @@
#endif
#ifdef DEVICE_POLLING
+extern int in_polling;
extern void init_device_poll(void);
extern void hardclock_device_poll(void);
#endif /* DEVICE_POLLING */
@@ -550,6 +551,11 @@
} else if (p != NULL) {
p->p_sticks++;
cp_time[CP_SYS]++;
+#if defined(DEVICE_POLLING)
+ } else if (in_polling) {
+ p->p_sticks++;
+ cp_time[CP_SYS]++;
+#endif
} else
cp_time[CP_IDLE]++;
}
Index: kern_poll.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/kern_poll.c,v
retrieving revision 1.2.2.4.1000.1
diff -U3 -r1.2.2.4.1000.1 kern_poll.c
--- kern_poll.c 10 Feb 2003 16:49:19 -0000 1.2.2.4.1000.1
+++ kern_poll.c 10 May 2003 23:37:11 -0000
@@ -54,6 +54,8 @@
void ether_poll(int); /* polling while in trap */
int idle_poll(void); /* poll while in idle loop */
+int in_polling;
+
/*
* Polling support for [network] device drivers.
*
@@ -268,11 +270,13 @@
{
if (poll_in_idle_loop && poll_handlers > 0) {
int s = splimp();
+ in_polling = 1;
enable_intr();
ether_poll(poll_each_burst);
disable_intr();
splx(s);
vm_page_zero_idle();
+ in_polling = 0;
return 1;
} else
return vm_page_zero_idle();
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