powerpc/pseries: Disable VPNH feature

Submitted by Benjamin Herrenschmidt on March 9, 2011, 11 p.m.

Details

Message ID 1299711614.22236.392.camel@pasglop
State Accepted, archived
Headers show

Commit Message

Benjamin Herrenschmidt March 9, 2011, 11 p.m.
This feature triggers nasty races in the scheduler between the
rebuilding of the topology and the load balancing code, causing
the machine to hang.

Disable it for now until the races are fixed.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

Jesse: I'm sending that to Linus now. We'll sort things out for the
next release.

Comments

Benjamin Herrenschmidt March 9, 2011, 11:07 p.m.
On Thu, 2011-03-10 at 10:00 +1100, Benjamin Herrenschmidt wrote:
> This feature triggers nasty races in the scheduler between the
> rebuilding of the topology and the load balancing code, causing
> the machine to hang.
> 
> Disable it for now until the races are fixed.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
> 
> Jesse: I'm sending that to Linus now. We'll sort things out for the
> next release.
> 
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index fd48123..74f1baa 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -1516,6 +1516,7 @@ int start_topology_update(void)
>  {
>  	int rc = 0;
>  
> +#if 0 /* Disabled until races with load balancing are fixed */
>  	if (firmware_has_feature(FW_FEATURE_VPHN) &&
>  	    get_lppaca()->shared_proc) {
>  		vphn_enabled = 1;
> @@ -1524,6 +1525,7 @@ int start_topology_update(void)
>  		set_topology_timer();
>  		rc = 1;
>  	}
> +#endif

Turning that into if (0 && instead to avoid compiler warnings
and thus build failures

Cheers,
Ben.

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diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index fd48123..74f1baa 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1516,6 +1516,7 @@  int start_topology_update(void)
 {
 	int rc = 0;
 
+#if 0 /* Disabled until races with load balancing are fixed */
 	if (firmware_has_feature(FW_FEATURE_VPHN) &&
 	    get_lppaca()->shared_proc) {
 		vphn_enabled = 1;
@@ -1524,6 +1525,7 @@  int start_topology_update(void)
 		set_topology_timer();
 		rc = 1;
 	}
+#endif
 
 	return rc;
 }