Le 19/05/2017 à 16:41, Anton Blanchard a écrit :
From: Anton Blanchard <an...@samba.org>
ppc64 is the only architecture that turns on VIRT_CPU_ACCOUNTING_NATIVE
by default. The overhead of this option is extremely high - a context
switch microbenchmark using sched_yield() is almost 20% slower.
To get finer grained user/hardirq/softirq statitics, the
IRQ_TIME_ACCOUNTING option can be used instead, which has much lower
overhead.
Does IRQ_TIME_ACCOUNTING allow the same granularity as
VIRT_CPU_ACCOUNTING_NATIVE ?
I've quickly looked into the source, it seems that this option still
accounts based on time ticks.
On a hardware doing mainly VoIP handling, the processes run a few ms
every 20 ms. With TICK_CPU_ACCOUNTING and a 10ms tick, the processes
either appear with 50% CPU or almost 0%.
Would it be more precise with IRQ_TIME_ACCOUNTING ?
Christophe
As such, disable this option by default. If a user really wants it,
they can still enable it manually.
Signed-off-by: Anton Blanchard <an...@samba.org>
---
init/Kconfig | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index 1d3475fc9496..a5c30acc1ede 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -342,8 +342,7 @@ config VIRT_CPU_ACCOUNTING
choice
prompt "Cputime accounting"
- default TICK_CPU_ACCOUNTING if !PPC64
- default VIRT_CPU_ACCOUNTING_NATIVE if PPC64
+ default TICK_CPU_ACCOUNTING
# Kind of a stub config for the pure tick based cputime accounting
config TICK_CPU_ACCOUNTING
