Re: [PATCH] Fake NUMA emulation for PowerPC (Take 2)

From: Balbir Singh
Date: Sat Jan 26 2008 - 02:13:56 EST


* Michael Ellerman <michael@xxxxxxxxxxxxxx> [2008-01-18 16:44:58]:

>
> This fixes it, although I'm a little worried about some of the
> removals/movings of node_set_online() in the patch.
>
>
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 1666e7d..dcedc26 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -49,7 +49,6 @@ static int __cpuinit fake_numa_create_new_node(unsigned long end_pfn,
> static unsigned int fake_nid = 0;
> static unsigned long long curr_boundary = 0;
>
> - *nid = fake_nid;
> if (!p)
> return 0;
>
> @@ -60,6 +59,7 @@ static int __cpuinit fake_numa_create_new_node(unsigned long end_pfn,
> if (mem < curr_boundary)
> return 0;
>
> + *nid = fake_nid;
> curr_boundary = mem;
>
> if ((end_pfn << PAGE_SHIFT) > mem) {
>

Hi, Michael,

Here's a better and more complete fix for the problem. Could you
please see if it works for you? I tested it on a real NUMA box and it
seemed to work fine there.

Description
-----------

This patch provides a fix for the problem found by
Michael Ellerman <michael@xxxxxxxxxxxxxx> while using fake NUMA nodes
on a cell box. The code modifies node id iff (as in if and only if)
fake NUMA nodes are created.

Signed-off-by: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
---

arch/powerpc/mm/numa.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff -puN arch/powerpc/mm/numa.c~fix-fake-numa-nid-on-numa arch/powerpc/mm/numa.c
--- linux-2.6.24-rc8/arch/powerpc/mm/numa.c~fix-fake-numa-nid-on-numa 2008-01-26 12:20:29.000000000 +0530
+++ linux-2.6.24-rc8-balbir/arch/powerpc/mm/numa.c 2008-01-26 12:27:53.000000000 +0530
@@ -49,7 +49,12 @@ static int __cpuinit fake_numa_create_ne
static unsigned int fake_nid = 0;
static unsigned long long curr_boundary = 0;

- *nid = fake_nid;
+ /*
+ * If we did enable fake nodes and cross a node,
+ * remember the last node and start from there.
+ */
+ if (fake_nid)
+ *nid = fake_nid;
if (!p)
return 0;

_

--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/