> > yet for one machine conf.nmach == 4 and for the
> > other conf.nmach == 16; neither is calling halt.
>
> Hypothesis: with four processors there's enough work to keep all
> the cpus busy. With sixteen processors you're getting i/o bound
> (where's the filesystem coming from?) so some of the cpus are
> idling, and would call halt if they were allowed to.
it seems to be a tad more complicated than that.
these machines "aren't doing anything"; i'm the only
one logged in, and they run no services.
16cpus; >/dev/kpctl echo startclr; sleep 5;>/dev/kpctl echo stop; \
kprof /386/9pccpu /dev/kpdata | sed 10q
total: 79782 in kernel text: 79782 outside kernel text: 0
KTZERO f0100000
ms % sym
60348 75.2 runproc
9125 11.3 _cycles
6230 7.7 perfticks
2696 3.3 isaconfig
1271 1.5 idlehands
1127 1.4 microdelay
1 0.0 freepte
4cpus; >/dev/kpctl echo startclr; sleep 5;>/dev/kpctl echo stop; \
kprof /386/9pccpu /dev/kpdata | sed 10q
total: 20327 in kernel text: 20327 outside kernel text: 0
KTZERO f0100000
ms % sym
8124 40.2 rebalance
5261 26.0 runproc
3252 16.1 _cycles
1997 9.9 perfticks
702 3.4 microdelay
548 2.7 idlehands
349 1.7 isaconfig
this trend continues with burncycles, a program
(attached) that actually does stuff on n cpus:
4cpus; for(i in 1 2 4){
>/dev/kpctl echo startclr;
>/dev/null time 8.burncycles $i;
>/dev/kpctl echo stop;
kprof /386/9pccpu /dev/kpdata|sed 10q
}
10.56u 0.00s 10.56r 8.burncycles 1
total: 42246 in kernel text: 31684 outside kernel text: 10562
KTZERO f0100000
ms % sym
12693 40.0 rebalance
8324 26.2 runproc
5215 16.4 _cycles
3182 10.0 perfticks
1088 3.4 microdelay
902 2.8 idlehands
611 1.9 isaconfig
10.56u 0.00s 10.56r 8.burncycles 2
total: 42561 in kernel text: 21441 outside kernel text: 21120
KTZERO f0100000
ms % sym
8567 39.9 rebalance
5558 25.9 runproc
3483 16.2 _cycles
2190 10.2 perfticks
742 3.4 microdelay
590 2.7 idlehands
408 1.9 isaconfig
10.56u 0.00s 10.56r 8.burncycles 4
total: 42524 in kernel text: 428 outside kernel text: 42096
KTZERO f0100000
ms % sym
159 37.1 rebalance
120 28.0 runproc
63 14.7 _cycles
49 11.4 perfticks
17 3.9 idlehands
9 2.1 isaconfig
9 2.1 microdelay
8cpus; for(i in 1 2 4 8 16){
>/dev/kpctl echo startclr;
>/dev/null time 8.burncycles $i;
>/dev/kpctl echo stop;
kprof /386/9pccpu /dev/kpdata|sed 10q
}
17.26u 0.00s 17.26r 8.burncycles 1
total: 265856 in kernel text: 248594 outside kernel text: 17262
KTZERO f0100000
ms % sym
191427 77.0 runproc
28607 11.5 _cycles
21218 8.5 perfticks
8618 3.4 isaconfig
4408 1.7 idlehands
3584 1.4 microdelay
1 0.0 nhgets
17.64u 0.00s 17.64r 8.burncycles 2
total: 276561 in kernel text: 241360 outside kernel text: 35201
KTZERO f0100000
ms % sym
181186 75.0 runproc
26816 11.1 _cycles
23267 9.6 perfticks
8049 3.3 isaconfig
4261 1.7 idlehands
3483 1.4 microdelay
2 0.0 sleep
18.87u 0.00s 18.87r 8.burncycles 4
total: 297021 in kernel text: 225113 outside kernel text: 71908
KTZERO f0100000
ms % sym
168136 74.6 runproc
24904 11.0 _cycles
22849 10.1 perfticks
7462 3.3 isaconfig
3879 1.7 idlehands
3058 1.3 microdelay
1 0.0 ilock
18.65u 0.00s 18.65r 8.burncycles 8
total: 289838 in kernel text: 148804 outside kernel text: 141034
KTZERO f0100000
ms % sym
117215 78.7 runproc
16729 11.2 _cycles
12872 8.6 perfticks
5119 3.4 isaconfig
2765 1.8 idlehands
2064 1.3 microdelay
2 0.0 sleep
19.34u 0.00s 19.35r 8.burncycles 16
total: 281308 in kernel text: -9895 outside kernel text: 291203
KTZERO f0100000
ms % sym
497 -5.0 runproc
78 0.-7 _cycles
50 0.-5 perfticks
14 0.-1 isaconfig
10 0.-1 microdelay
8 0.0 idlehands
1 0.0 ilock
- erik#include <u.h>
#include <libc.h>
#include <thread.h>
#define Scale (100000000000ull)
/*
* waste time
*/
vlong
πjj(uint j)
{
vlong v;
v = 4*Scale / (2*j + 1);
if(j&1)
return -v;
return v;
}
vlong
π(void)
{
uint i;
vlong v;
v = 0;
for(i = 0; i < 500000000; i++)
v += πjj(i);
return v;
}
void
p(void *v)
{
int i;
i = (int)v;
print("%d: %lld\n", i, π());
threadexits("");
}
void
usage(void)
{
fprint(2, "usage: burncycles nthread\n");
threadexits("usage");
}
void
threadmain(int argc, char **argv)
{
int n, i;
ARGBEGIN{
default:
usage();
}ARGEND
n = 1;
else if(argc > 1 || (n = atoi(argv[0])) <= 0)
usage();
for(i = 0; i < n-1; i++)
proccreate(p, (void*)i, 4096);
p((void*)i);
}
