Subject: [PATCH] powerpc: Fix hypervisor TLB batching

From: Anton Blanchard <[email-masked]>
Date: Mon, 12 Oct 2009 18:47:34 +1100

Profiling of a page fault scalability microbenchmark shows flush_hash_range
is not calling the batch hpte invalidate hcall (H_BULK_REMOVE).

It turns out we have a duplicate firmware feature for hcall-bulk and the
current setup code stops after finding the first match. This meant we never
batch and always do individual invalidates.

The patch below removes the duplicate and shifts FW_FEATURE_CMO to close
the gap. With the patch applied the single threaded page fault rate improves
from 217169 to 238755 per second on a POWER5 test box, a 10% improvement.

Signed-off-by: Anton Blanchard <[email-masked]>
---

Index: linux.trees.git/arch/powerpc/include/asm/firmware.h
===================================================================
--- linux.trees.git.orig/arch/powerpc/include/asm/firmware.h	2009-10-12 18:11:56.000000000 +1100
+++ linux.trees.git/arch/powerpc/include/asm/firmware.h	2009-10-12 18:21:20.000000000 +1100
@@ -37,7 +37,7 @@
 #define FW_FEATURE_VIO		ASM_CONST(0x0000000000004000)
 #define FW_FEATURE_RDMA		ASM_CONST(0x0000000000008000)
 #define FW_FEATURE_LLAN		ASM_CONST(0x0000000000010000)
-#define FW_FEATURE_BULK		ASM_CONST(0x0000000000020000)
+#define FW_FEATURE_BULK_REMOVE	ASM_CONST(0x0000000000020000)
 #define FW_FEATURE_XDABR	ASM_CONST(0x0000000000040000)
 #define FW_FEATURE_MULTITCE	ASM_CONST(0x0000000000080000)
 #define FW_FEATURE_SPLPAR	ASM_CONST(0x0000000000100000)
@@ -45,8 +45,7 @@
 #define FW_FEATURE_LPAR		ASM_CONST(0x0000000000400000)
 #define FW_FEATURE_PS3_LV1	ASM_CONST(0x0000000000800000)
 #define FW_FEATURE_BEAT		ASM_CONST(0x0000000001000000)
-#define FW_FEATURE_BULK_REMOVE	ASM_CONST(0x0000000002000000)
-#define FW_FEATURE_CMO		ASM_CONST(0x0000000004000000)
+#define FW_FEATURE_CMO		ASM_CONST(0x0000000002000000)
 
 #ifndef __ASSEMBLY__
 
@@ -58,8 +57,9 @@ enum {
 		FW_FEATURE_PERF | FW_FEATURE_DUMP | FW_FEATURE_INTERRUPT |
 		FW_FEATURE_MIGRATE | FW_FEATURE_PERFMON | FW_FEATURE_CRQ |
 		FW_FEATURE_VIO | FW_FEATURE_RDMA | FW_FEATURE_LLAN |
-		FW_FEATURE_BULK | FW_FEATURE_XDABR | FW_FEATURE_MULTITCE |
-		FW_FEATURE_SPLPAR | FW_FEATURE_LPAR | FW_FEATURE_CMO,
+		FW_FEATURE_BULK_REMOVE | FW_FEATURE_XDABR |
+		FW_FEATURE_MULTITCE | FW_FEATURE_SPLPAR | FW_FEATURE_LPAR |
+		FW_FEATURE_CMO,
 	FW_FEATURE_PSERIES_ALWAYS = 0,
 	FW_FEATURE_ISERIES_POSSIBLE = FW_FEATURE_ISERIES | FW_FEATURE_LPAR,
 	FW_FEATURE_ISERIES_ALWAYS = FW_FEATURE_ISERIES | FW_FEATURE_LPAR,
Index: linux.trees.git/arch/powerpc/platforms/pseries/firmware.c
===================================================================
--- linux.trees.git.orig/arch/powerpc/platforms/pseries/firmware.c	2009-10-12 18:08:37.000000000 +1100
+++ linux.trees.git/arch/powerpc/platforms/pseries/firmware.c	2009-10-12 18:12:54.000000000 +1100
@@ -51,11 +51,10 @@ firmware_features_table[FIRMWARE_MAX_FEA
 	{FW_FEATURE_VIO,		"hcall-vio"},
 	{FW_FEATURE_RDMA,		"hcall-rdma"},
 	{FW_FEATURE_LLAN,		"hcall-lLAN"},
-	{FW_FEATURE_BULK,		"hcall-bulk"},
+	{FW_FEATURE_BULK_REMOVE,	"hcall-bulk"},
 	{FW_FEATURE_XDABR,		"hcall-xdabr"},
 	{FW_FEATURE_MULTITCE,		"hcall-multi-tce"},
 	{FW_FEATURE_SPLPAR,		"hcall-splpar"},
-	{FW_FEATURE_BULK_REMOVE,	"hcall-bulk"},
 };
 
 /* Build up the firmware features bitmask using the contents of