On 21/10/16 14:05, Peter Zijlstra wrote:

On Fri, Oct 21, 2016 at 01:58:55PM +0200, Christian Borntraeger wrote:

quoted

stop_machine can take a very long time if the hypervisor does
overcommitment for guest CPUs. When waiting for "the one", lets
give up our CPU by using the new cpu_relax_yield.

This seems something that would apply to most other virt stuff. Lets Cc
a few more lists for that.

Corrected xen-devel mail address.


Juergen

quoted

Signed-off-by: Christian Borntraeger <redacted>
---
 kernel/stop_machine.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index ec9ab2f..1eb8266 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c

@@ -194,7 +194,7 @@ static int multi_cpu_stop(void *data)
 	/* Simple state machine */
 	do {
 		/* Chill out and ensure we re-read multi_stop_state. */
-		cpu_relax();
+		cpu_relax_yield();
 		if (msdata->state != curstate) {
 			curstate = msdata->state;
 			switch (curstate) {

-- 
2.5.5

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