Patchwork powerpc/pseries: Disable VPNH feature

login
register
mail settings
Submitter Benjamin Herrenschmidt
Date March 9, 2011, 11 p.m.
Message ID <1299711614.22236.392.camel@pasglop>
Download mbox | patch
Permalink /patch/86162/
State Accepted, archived
Headers show

Comments

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.
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.

Patch

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;
 }