diff options
| author | Christophe Leroy | 2018-08-02 09:53:59 +0200 |
|---|---|---|
| committer | Michael Ellerman | 2018-10-20 04:26:47 +0200 |
| commit | abcff86df2d2ec0a0ca9470fa5d2a184af18928a (patch) | |
| tree | 75fa912a58d6371828a653a393d7b766d0d4649b /arch/powerpc/include/asm/accounting.h | |
| parent | powerpc/time: isolate scaled cputime accounting in dedicated functions. (diff) | |
| download | kernel-qcow2-linux-abcff86df2d2ec0a0ca9470fa5d2a184af18928a.tar.gz kernel-qcow2-linux-abcff86df2d2ec0a0ca9470fa5d2a184af18928a.tar.xz kernel-qcow2-linux-abcff86df2d2ec0a0ca9470fa5d2a184af18928a.zip | |
powerpc/time: Only set CONFIG_ARCH_HAS_SCALED_CPUTIME on PPC64
scaled cputime is only meaningfull when the processor has
SPURR and/or PURR, which means only on PPC64.
Removing it on PPC32 significantly reduces the size of
vtime_account_system() and vtime_account_idle() on an 8xx:
Before:
00000000 l F .text 000000a8 vtime_delta
00000280 g F .text 0000010c vtime_account_system
0000038c g F .text 00000048 vtime_account_idle
After:
(vtime_delta gets inlined inside the two functions)
000001d8 g F .text 000000a0 vtime_account_system
00000278 g F .text 00000038 vtime_account_idle
In terms of performance, we also get approximatly 7% improvement on
task switch. The following small benchmark app is run with perf stat:
void *thread(void *arg)
{
int i;
for (i = 0; i < atoi((char*)arg); i++)
pthread_yield();
}
int main(int argc, char **argv)
{
pthread_t th1, th2;
pthread_create(&th1, NULL, thread, argv[1]);
pthread_create(&th2, NULL, thread, argv[1]);
pthread_join(th1, NULL);
pthread_join(th2, NULL);
return 0;
}
Before the patch:
Performance counter stats for 'chrt -f 98 ./sched 100000' (50 runs):
8228.476465 task-clock (msec) # 0.954 CPUs utilized ( +- 0.23% )
200004 context-switches # 0.024 M/sec ( +- 0.00% )
After the patch:
Performance counter stats for 'chrt -f 98 ./sched 100000' (50 runs):
7649.070444 task-clock (msec) # 0.955 CPUs utilized ( +- 0.27% )
200004 context-switches # 0.026 M/sec ( +- 0.00% )
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include/asm/accounting.h')
| -rw-r--r-- | arch/powerpc/include/asm/accounting.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/accounting.h b/arch/powerpc/include/asm/accounting.h index 3abcf98ed2e0..c607c5d835cc 100644 --- a/arch/powerpc/include/asm/accounting.h +++ b/arch/powerpc/include/asm/accounting.h @@ -15,8 +15,10 @@ struct cpu_accounting_data { /* Accumulated cputime values to flush on ticks*/ unsigned long utime; unsigned long stime; +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME unsigned long utime_scaled; unsigned long stime_scaled; +#endif unsigned long gtime; unsigned long hardirq_time; unsigned long softirq_time; @@ -25,8 +27,10 @@ struct cpu_accounting_data { /* Internal counters */ unsigned long starttime; /* TB value snapshot */ unsigned long starttime_user; /* TB value on exit to usermode */ +#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME unsigned long startspurr; /* SPURR value snapshot */ unsigned long utime_sspurr; /* ->user_time when ->startspurr set */ +#endif }; #endif |