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Subject[PATCH] x86: UV BAU Increase maximum CPUs per socket/hub
Date
We have encountered hardware with 18 cores/socket that gives 36 CPUs/socket
with hyperthreading enabled. This exceeds the current MAX_CPUS_PER_SOCKET
causing a failure in get_cpu_topology. Increase MAX_CPUS_PER_SOCKET to 64
and MAX_CPUS_PER_UVHUB to 128.

Additionally, this exposed another bug. When get_cpu_topology fails, we
need to make sure that we do not use bau_control->statp (e.g. when a
user reads /proc/sgi_uv/ptc_statistics causing ptc_seq_show to be
invoked). In uv_bau_init we call set_bau_off() when
init_per_cpu()->get_cpu_topology() fails -- therefore, to avoid
referencing a NULL pointer we add code that detects when the bau is off
and print out the bau is disabled.

Signed-off-by: James Custer <jcuster@sgi.com>
---
arch/x86/include/asm/uv/uv_bau.h | 4 ++--
arch/x86/platform/uv/tlb_uv.c | 4 ++++
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/uv/uv_bau.h b/arch/x86/include/asm/uv/uv_bau.h
index 2d60a78..fc808b8 100644
--- a/arch/x86/include/asm/uv/uv_bau.h
+++ b/arch/x86/include/asm/uv/uv_bau.h
@@ -33,8 +33,8 @@
* Each of the descriptors is 64 bytes in size (8*64 = 512 bytes in a set).
*/

-#define MAX_CPUS_PER_UVHUB 64
-#define MAX_CPUS_PER_SOCKET 32
+#define MAX_CPUS_PER_UVHUB 128
+#define MAX_CPUS_PER_SOCKET 64
#define ADP_SZ 64 /* hardware-provided max. */
#define UV_CPUS_PER_AS 32 /* hardware-provided max. */
#define ITEMS_PER_DESC 8
diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index 3968d67..570b1b1 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -1384,6 +1384,10 @@ static int ptc_seq_show(struct seq_file *file, void *data)
}
if (cpu < num_possible_cpus() && cpu_online(cpu)) {
bcp = &per_cpu(bau_control, cpu);
+ if (bcp->nobau) {
+ seq_printf(file, "cpu %d bau disabled\n", cpu);
+ return 0;
+ }
stat = bcp->statp;
/* source side statistics */
seq_printf(file,
--
1.8.2.1


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