linux-dev - Linux kernel development work

Age	Commit message (Collapse)	Author	Files	Lines
2018-10-20	powerpc/time: Only set CONFIG_ARCH_HAS_SCALED_CPUTIME on PPC64	Christophe Leroy	1	-0/+4
	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>
2017-01-14	sched/cputime, powerpc: Prepare accounting structure for cputime flush on tick	Frederic Weisbecker	1	-3/+11
	In order to prepare for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y to delay cputime accounting to the tick, provide finegrained accumulators to powerpc in order to store the cputime until flushing. While at it, normalize the name of several fields according to common cputime naming. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Link: http://lkml.kernel.org/r/1483636310-6557-6-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-09	powerpc32: provide VIRT_CPU_ACCOUNTING	Christophe Leroy	1	-0/+24
	This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture. PPC32 doesn't have the PACA structure, so we use the task_info structure to store the accounting data. In order to reuse on PPC32 the PPC64 functions, all u64 data has been replaced by 'unsigned long' so that it is u32 on PPC32 and u64 on PPC64 Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Scott Wood <oss@buserror.net>