A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-30 11:41:38 -04:00
Code Issues Projects Releases Packages Wiki Activity

mutex: have non-spinning mutexes on s390 by default

Browse source 
Impact: performance regression fix for s390

The adaptive spinning mutexes will not always do what one would expect on
virtualized architectures like s390. Especially the cpu_relax() loop in
mutex_spin_on_owner might hurt if the mutex holding cpu has been scheduled
away by the hypervisor.

We would end up in a cpu_relax() loop when there is no chance that the
state of the mutex changes until the target cpu has been scheduled again by
the hypervisor.

For that reason we should change the default behaviour to no-spin on s390.

We do have an instruction which allows to yield the current cpu in favour of
a different target cpu. Also we have an instruction which allows us to figure
out if the target cpu is physically backed.

However we need to do some performance tests until we can come up with
a solution that will do the right thing on s390.

Signed-off-by: Heiko Carstens <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Christian Borntraeger <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Heiko Carstens 2009-04-09 18:48:34 +02:00 • committed by Ingo Molnar
commit 36cd3c9f92
3 changed files with 6 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

3
arch/Kconfig
View file

@ -109,3 +109,6 @@ config HAVE_CLK
config HAVE_DMA_API_DEBUG
bool
config HAVE_DEFAULT_NO_SPIN_MUTEXES
bool