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SubjectRe: [patch 0/2] x86, UV: fixups for configurations with a large number of nodes.
On Fri, Oct 16, 2009 at 08:34:05AM +0200, Ingo Molnar wrote:
>
> * Robin Holt <holt@sgi.com> wrote:
>
> > We need the __uv_hub_info structure to contain the correct values for
> > n_val, gpa_mask, and lowmem_remap_*. The first patch in the series
> > accomplishes this. Could this be included in the stable tree as well.
> > Without this patch, booting a large configuration hits a problem where
> > the upper bits of the gnode affect the pnode and the bau will not
> > operate.
>
> i've applied this one.

Thank you for applying this one.

> > The second patch cleans up the broadcast assist unit code a small bit.
>
> Seems to be more than just a 'cleanup'. It changes:

I am going to rearrange a bit:

> + return gpa >> uv_hub_info->m_val & ((1UL << uv_hub_info->n_val) - 1);
>
> note that >> has higher priority than bitwise & - is that intended? I
> think the intention was:
>
> + return gpa >> (uv_hub_info->m_val & ((1UL << uv_hub_info->n_val) - 1));

The intention was (gpa >> m_val) & (n_mask); I love the clarity of
making it an explicitly stated mask. Much more readable.

>
> uv_nshift = uv_hub_info->m_val;
>
> to (in essence):
>
> uv_hub_info->m_val & ((1UL << uv_hub_info->n_val) - 1)
>
> which is not the same. Furthermore, the new inline is:

You have an excellent point there. That was a bug as well. That may
explain a few of our currently unexplained bau hangs. The value is
supposed to be a pnode instead of the current gnode.

Robin

---
Create an inline function to extract the pnode from a global physical
address and then convert the broadcast assist unit to use the newly
created uv_gpa_to_pnode function.

To: Ingo Molnar <mingo@elte.hu>
To: tglx@linutronix.de
Signed-off-by: Robin Holt <holt@sgi.com>
Acked-by: Cliff Whickman <cpw@sgi.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org

---
arch/x86/include/asm/uv/uv_hub.h | 16 +++++++++++++++-
arch/x86/kernel/tlb_uv.c | 7 ++-----
2 files changed, 17 insertions(+), 6 deletions(-)
Index: linux/arch/x86/include/asm/uv/uv_hub.h
===================================================================
--- linux.orig/arch/x86/include/asm/uv/uv_hub.h 2009-10-16 06:02:23.000000000 -0500
+++ linux/arch/x86/include/asm/uv/uv_hub.h 2009-10-16 06:07:52.000000000 -0500
@@ -114,7 +114,7 @@
/*
* The largest possible NASID of a C or M brick (+ 2)
*/
-#define UV_MAX_NASID_VALUE (UV_MAX_NUMALINK_NODES * 2)
+#define UV_MAX_NASID_VALUE (UV_MAX_NUMALINK_BLADES * 2)

struct uv_scir_s {
struct timer_list timer;
@@ -230,6 +230,20 @@ static inline unsigned long uv_gpa(void
return uv_soc_phys_ram_to_gpa(__pa(v));
}

+/* gnode -> pnode */
+static inline unsigned long uv_gpa_to_gnode(unsigned long gpa)
+{
+ return gpa >> uv_hub_info->m_val;
+}
+
+/* gpa -> pnode */
+static inline int uv_gpa_to_pnode(unsigned long gpa)
+{
+ unsigned long n_mask = (1UL << uv_hub_info->n_val) - 1;
+
+ return uv_gpa_to_gnode(gpa) & n_mask;
+}
+
/* pnode, offset --> socket virtual */
static inline void *uv_pnode_offset_to_vaddr(int pnode, unsigned long offset)
{
Index: linux/arch/x86/kernel/tlb_uv.c
===================================================================
--- linux.orig/arch/x86/kernel/tlb_uv.c 2009-10-16 06:02:27.000000000 -0500
+++ linux/arch/x86/kernel/tlb_uv.c 2009-10-16 06:02:28.000000000 -0500
@@ -23,8 +23,6 @@
static struct bau_control **uv_bau_table_bases __read_mostly;
static int uv_bau_retry_limit __read_mostly;

-/* position of pnode (which is nasid>>1): */
-static int uv_nshift __read_mostly;
/* base pnode in this partition */
static int uv_partition_base_pnode __read_mostly;

@@ -723,7 +721,7 @@ uv_activation_descriptor_init(int node,
BUG_ON(!adp);

pa = uv_gpa(adp); /* need the real nasid*/
- n = pa >> uv_nshift;
+ n = uv_gpa_to_pnode(pa);
m = pa & uv_mmask;

uv_write_global_mmr64(pnode, UVH_LB_BAU_SB_DESCRIPTOR_BASE,
@@ -778,7 +776,7 @@ uv_payload_queue_init(int node, int pnod
* need the pnode of where the memory was really allocated
*/
pa = uv_gpa(pqp);
- pn = pa >> uv_nshift;
+ pn = uv_gpa_to_pnode(pa);
uv_write_global_mmr64(pnode,
UVH_LB_BAU_INTD_PAYLOAD_QUEUE_FIRST,
((unsigned long)pn << UV_PAYLOADQ_PNODE_SHIFT) |
@@ -843,7 +841,6 @@ static int __init uv_bau_init(void)
GFP_KERNEL, cpu_to_node(cur_cpu));

uv_bau_retry_limit = 1;
- uv_nshift = uv_hub_info->m_val;
uv_mmask = (1UL << uv_hub_info->m_val) - 1;
nblades = uv_num_possible_blades();


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