Re: Off topic: Numactl "distance" wrong

From: David Rientjes
Date: Tue Apr 07 2009 - 03:44:49 EST


On Tue, 7 Apr 2009, Andi Kleen wrote:

> I'm not aware of any that does. In general applications usually
> only use the bare basics of NUMA API (if at all), the fancy stuff tends
> to be more slideware.
>
> If it's true then the correct place would be to fix the BIOS.
>

We already verify that each node has local distance to itself and that its
distance to any other node is greater than local when determining whether
the SLIT is valid.

It would also be possible to verify that the distance between two
localities is described consistently in the table (like in the following
patch).

I do think it would be helpful to add an acpi=noslit option, however, that
would disable parsing the SLIT if it is known to incorrectly describe the
physical topology of the system.
---
diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
--- a/drivers/acpi/numa.c
+++ b/drivers/acpi/numa.c
@@ -172,6 +172,8 @@ static __init int slit_valid(struct acpi_table_slit *slit)
return 0;
} else if (val <= LOCAL_DISTANCE)
return 0;
+ if (val != slit->entry[d*j + i])
+ return 0;
}
}
return 1;
--
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