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authorAnton Blanchard <anton@samba.org>2012-05-29 19:33:12 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-07-03 14:14:44 +1000
commitfde69282b7ba2701560764b81ebb756deb98cf2b (patch)
treee350f7d55f90885e9ea9ee26dcb020f0fbcbaa4e
parent6f7839e542ee18770288be75114bd2e6771e1421 (diff)
downloadlinux-fde69282b7ba2701560764b81ebb756deb98cf2b.tar.gz
powerpc: POWER7 optimised copy_page using VMX and enhanced prefetch
Implement a POWER7 optimised copy_page using VMX and enhanced prefetch instructions. We use enhanced prefetch hints to prefetch both the load and store side. We copy a cacheline at a time and fall back to regular loads and stores if we are unable to use VMX (eg we are in an interrupt). The following microbenchmark was used to assess the impact of the patch: http://ozlabs.org/~anton/junkcode/page_fault_file.c We test MAP_PRIVATE page faults across a 1GB file, 100 times: # time ./page_fault_file -p -l 1G -i 100 Before: 22.25s After: 18.89s 17% faster Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/lib/Makefile2
-rw-r--r--arch/powerpc/lib/copypage_64.S4
-rw-r--r--arch/powerpc/lib/copypage_power7.S168
-rw-r--r--arch/powerpc/lib/vmx-helper.c23
4 files changed, 196 insertions, 1 deletions
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 1eb94c7af6c..873805ec3ed 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -17,7 +17,7 @@ obj-$(CONFIG_HAS_IOMEM) += devres.o
obj-$(CONFIG_PPC64) += copypage_64.o copyuser_64.o \
memcpy_64.o usercopy_64.o mem_64.o string.o \
checksum_wrappers_64.o hweight_64.o \
- copyuser_power7.o string_64.o
+ copyuser_power7.o string_64.o copypage_power7.o
obj-$(CONFIG_XMON) += sstep.o ldstfp.o
obj-$(CONFIG_KPROBES) += sstep.o ldstfp.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += sstep.o ldstfp.o
diff --git a/arch/powerpc/lib/copypage_64.S b/arch/powerpc/lib/copypage_64.S
index 53dcb6b1b70..9f9434a8526 100644
--- a/arch/powerpc/lib/copypage_64.S
+++ b/arch/powerpc/lib/copypage_64.S
@@ -17,7 +17,11 @@ PPC64_CACHES:
.section ".text"
_GLOBAL(copy_page)
+BEGIN_FTR_SECTION
lis r5,PAGE_SIZE@h
+FTR_SECTION_ELSE
+ b .copypage_power7
+ALT_FTR_SECTION_END_IFCLR(CPU_FTR_VMX_COPY)
ori r5,r5,PAGE_SIZE@l
BEGIN_FTR_SECTION
ld r10,PPC64_CACHES@toc(r2)
diff --git a/arch/powerpc/lib/copypage_power7.S b/arch/powerpc/lib/copypage_power7.S
new file mode 100644
index 00000000000..01e2b5db325
--- /dev/null
+++ b/arch/powerpc/lib/copypage_power7.S
@@ -0,0 +1,168 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2012
+ *
+ * Author: Anton Blanchard <anton@au.ibm.com>
+ */
+#include <asm/page.h>
+#include <asm/ppc_asm.h>
+
+#define STACKFRAMESIZE 256
+#define STK_REG(i) (112 + ((i)-14)*8)
+
+_GLOBAL(copypage_power7)
+ /*
+ * We prefetch both the source and destination using enhanced touch
+ * instructions. We use a stream ID of 0 for the load side and
+ * 1 for the store side. Since source and destination are page
+ * aligned we don't need to clear the bottom 7 bits of either
+ * address.
+ */
+ ori r9,r3,1 /* stream=1 */
+
+#ifdef CONFIG_PPC_64K_PAGES
+ lis r7,0x0E01 /* depth=7, units=512 */
+#else
+ lis r7,0x0E00 /* depth=7 */
+ ori r7,r7,0x1000 /* units=32 */
+#endif
+ ori r10,r7,1 /* stream=1 */
+
+ lis r8,0x8000 /* GO=1 */
+ clrldi r8,r8,32
+
+.machine push
+.machine "power4"
+ dcbt r0,r4,0b01000
+ dcbt r0,r7,0b01010
+ dcbtst r0,r9,0b01000
+ dcbtst r0,r10,0b01010
+ eieio
+ dcbt r0,r8,0b01010 /* GO */
+.machine pop
+
+#ifdef CONFIG_ALTIVEC
+ mflr r0
+ std r3,48(r1)
+ std r4,56(r1)
+ std r0,16(r1)
+ stdu r1,-STACKFRAMESIZE(r1)
+ bl .enter_vmx_copy
+ cmpwi r3,0
+ ld r0,STACKFRAMESIZE+16(r1)
+ ld r3,STACKFRAMESIZE+48(r1)
+ ld r4,STACKFRAMESIZE+56(r1)
+ mtlr r0
+
+ li r0,(PAGE_SIZE/128)
+ mtctr r0
+
+ beq .Lnonvmx_copy
+
+ addi r1,r1,STACKFRAMESIZE
+
+ li r6,16
+ li r7,32
+ li r8,48
+ li r9,64
+ li r10,80
+ li r11,96
+ li r12,112
+
+ .align 5
+1: lvx vr7,r0,r4
+ lvx vr6,r4,r6
+ lvx vr5,r4,r7
+ lvx vr4,r4,r8
+ lvx vr3,r4,r9
+ lvx vr2,r4,r10
+ lvx vr1,r4,r11
+ lvx vr0,r4,r12
+ addi r4,r4,128
+ stvx vr7,r0,r3
+ stvx vr6,r3,r6
+ stvx vr5,r3,r7
+ stvx vr4,r3,r8
+ stvx vr3,r3,r9
+ stvx vr2,r3,r10
+ stvx vr1,r3,r11
+ stvx vr0,r3,r12
+ addi r3,r3,128
+ bdnz 1b
+
+ b .exit_vmx_copy /* tail call optimise */
+
+#else
+ li r0,(PAGE_SIZE/128)
+ mtctr r0
+
+ stdu r1,-STACKFRAMESIZE(r1)
+#endif
+
+.Lnonvmx_copy:
+ std r14,STK_REG(r14)(r1)
+ std r15,STK_REG(r15)(r1)
+ std r16,STK_REG(r16)(r1)
+ std r17,STK_REG(r17)(r1)
+ std r18,STK_REG(r18)(r1)
+ std r19,STK_REG(r19)(r1)
+ std r20,STK_REG(r20)(r1)
+
+1: ld r0,0(r4)
+ ld r5,8(r4)
+ ld r6,16(r4)
+ ld r7,24(r4)
+ ld r8,32(r4)
+ ld r9,40(r4)
+ ld r10,48(r4)
+ ld r11,56(r4)
+ ld r12,64(r4)
+ ld r14,72(r4)
+ ld r15,80(r4)
+ ld r16,88(r4)
+ ld r17,96(r4)
+ ld r18,104(r4)
+ ld r19,112(r4)
+ ld r20,120(r4)
+ addi r4,r4,128
+ std r0,0(r3)
+ std r5,8(r3)
+ std r6,16(r3)
+ std r7,24(r3)
+ std r8,32(r3)
+ std r9,40(r3)
+ std r10,48(r3)
+ std r11,56(r3)
+ std r12,64(r3)
+ std r14,72(r3)
+ std r15,80(r3)
+ std r16,88(r3)
+ std r17,96(r3)
+ std r18,104(r3)
+ std r19,112(r3)
+ std r20,120(r3)
+ addi r3,r3,128
+ bdnz 1b
+
+ ld r14,STK_REG(r14)(r1)
+ ld r15,STK_REG(r15)(r1)
+ ld r16,STK_REG(r16)(r1)
+ ld r17,STK_REG(r17)(r1)
+ ld r18,STK_REG(r18)(r1)
+ ld r19,STK_REG(r19)(r1)
+ ld r20,STK_REG(r20)(r1)
+ addi r1,r1,STACKFRAMESIZE
+ blr
diff --git a/arch/powerpc/lib/vmx-helper.c b/arch/powerpc/lib/vmx-helper.c
index 753a839f4a1..3cf529ceec5 100644
--- a/arch/powerpc/lib/vmx-helper.c
+++ b/arch/powerpc/lib/vmx-helper.c
@@ -49,3 +49,26 @@ int exit_vmx_usercopy(void)
pagefault_enable();
return 0;
}
+
+int enter_vmx_copy(void)
+{
+ if (in_interrupt())
+ return 0;
+
+ preempt_disable();
+
+ enable_kernel_altivec();
+
+ return 1;
+}
+
+/*
+ * All calls to this function will be optimised into tail calls. We are
+ * passed a pointer to the destination which we return as required by a
+ * memcpy implementation.
+ */
+void *exit_vmx_copy(void *dest)
+{
+ preempt_enable();
+ return dest;
+}