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authorAnton Blanchard <anton@samba.org>2011-04-07 01:54:07 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-04-27 14:18:50 +1000
commiteca590f402332ab873d13f2d8d00fa0b91cfff36 (patch)
tree1dc942f6c0983ae59cfe2692d2d339345a995a1d
parenta7b8ad405862fb10e496ce839d423dfc94ac821b (diff)
downloadlinaro-lsk-eca590f402332ab873d13f2d8d00fa0b91cfff36.tar.gz
powerpc/rtas: Only sleep in rtas_busy_delay if we have useful work to do
RTAS returns extended error codes as a hint of how long the OS might want to wait before retrying a call. If we have nothing else useful to do we may as well call back straight away. This was found when testing the new dynamic dma window feature. Firmware split the zeroing of the TCE table into 32k chunks but returned 9901 (which is a suggested wait of 10ms). All up this took about 10 minutes to complete since msleep is jiffies based and will round 10ms up to 20ms. With the patch below we take 3 seconds to complete the same test. The hint firmware is returning in the RTAS call should definitely be decreased, but even if we slept 1ms each iteration this would take 32s. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/kernel/rtas.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 2097f2b3cba..f48446635c8 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -494,7 +494,7 @@ unsigned int rtas_busy_delay(int status)
might_sleep();
ms = rtas_busy_delay_time(status);
- if (ms)
+ if (ms && need_resched())
msleep(ms);
return ms;