summaryrefslogtreecommitdiffstats
path: root/arch/arc/Kconfig
diff options
context:
space:
mode:
authorVineet Gupta <vgupta@synopsys.com>2015-07-14 19:50:18 +0530
committerVineet Gupta <vgupta@synopsys.com>2015-08-04 09:26:34 +0530
commite78fdfef84be13a5c2b8276e12203cdf24778596 (patch)
treee16fad7f1d73a651d2f02deefd8f20f5bf9a018e /arch/arc/Kconfig
parent69cbe630f54ec02efe47fdb9e257e617161da370 (diff)
downloadlinux-e78fdfef84be13a5c2b8276e12203cdf24778596.tar.bz2
ARCv2: spinlock/rwlock/atomics: Delayed retry of failed SCOND with exponential backoff
This is to workaround the llock/scond livelock HS38x4 could get into a LLOCK/SCOND livelock in case of multiple overlapping coherency transactions in the SCU. The exclusive line state keeps rotating among contenting cores leading to a never ending cycle. So break the cycle by deferring the retry of failed exclusive access (SCOND). The actual delay needed is function of number of contending cores as well as the unrelated coherency traffic from other cores. To keep the code simple, start off with small delay of 1 which would suffice most cases and in case of contention double the delay. Eventually the delay is sufficient such that the coherency pipeline is drained, thus a subsequent exclusive access would succeed. Link: http://lkml.kernel.org/r/1438612568-28265-1-git-send-email-vgupta@synopsys.com Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc/Kconfig')
-rw-r--r--arch/arc/Kconfig5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index a5fccdfbfc8f..bd4670d1b89b 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -365,6 +365,11 @@ config ARC_HAS_LLSC
default y
depends on !ARC_CANT_LLSC
+config ARC_STAR_9000923308
+ bool "Workaround for llock/scond livelock"
+ default y
+ depends on ISA_ARCV2 && SMP && ARC_HAS_LLSC
+
config ARC_HAS_SWAPE
bool "Insn: SWAPE (endian-swap)"
default y