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[4/5] ARM64: Patch in prefetching for copy_page is requested

Message ID 1452668899-3553-5-git-send-email-apinski@cavium.com
State New
Headers show

Commit Message

Andrew Pinski Jan. 13, 2016, 7:08 a.m. UTC 
On ThunderX T88 pass 1 and pass 2, there is no
hardware prefetching so we need to patch in
software prefetching.  Prefetching improves this code
by 60% over the original code and 2x over the code
without prefetching.

Meaured by using the benchmark code at
https://github.com/apinski-cavium/copy_page_benchmark

Signed-off-by: Andrew Pinski <apinski@cavium.com>

---
 arch/arm64/lib/copy_page.S |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)

-- 
1.7.2.5
diff mbox

Patch

diff --git a/arch/arm64/lib/copy_page.S b/arch/arm64/lib/copy_page.S
index dfb0316..876e882 100644
--- a/arch/arm64/lib/copy_page.S
+++ b/arch/arm64/lib/copy_page.S
@@ -18,6 +18,8 @@ 
 #include <linux/const.h>
 #include <asm/assembler.h>
 #include <asm/page.h>
+#include <asm/cpufeature.h>
+#include <asm/alternative.h>
 
 
 /*
@@ -28,6 +30,15 @@ 
  *	x1 - src
  */
 ENTRY(copy_page)
+alternative_if_not ARM64_NEEDS_PREFETCH_128
+	nop
+	nop
+alternative_else
+	# Prefetch two cache lines ahead.
+	prfm    pldl1strm, [x1, #128]
+	prfm    pldl1strm, [x1, #256]
+alternative_endif
+
 	ldp	x2, x3, [x1]
 	ldp	x4, x5, [x1, #16]
 	ldp	x6, x7, [x1, #32]
@@ -42,6 +53,12 @@  ENTRY(copy_page)
 1:
 	subs	x18, x18, #128
 
+alternative_if_not ARM64_NEEDS_PREFETCH_128
+	nop
+alternative_else
+	prfm    pldl1strm, [x1, #384]
+alternative_endif
+
 	stnp	x2, x3, [x0]
 	ldp	x2, x3, [x1]
 	stnp	x4, x5, [x0, #16]