[dpdk-dev] [PATCH v2 2/2] Fix prefetch instruction on IBM POWER8

Chao Zhu chaozhu at linux.vnet.ibm.com
Wed Mar 30 17:39:17 CEST 2016


Current prefetch instruction (dcbt) implementation for IBM POWER8 has wrong
Touch Hint(TH) parameter. The current setting of TH=1 indicates to load data from
current cache line and an unlimited number of sequentially following cache lines.
TTH=0 means to load data from current cache line. rte_prefetch0 function is defined
to load one cache line, which means TH=0 is suited here.

Signed-off-by: Chao Zhu <chaozhu at linux.vnet.ibm.com>
---
 .../common/include/arch/ppc_64/rte_prefetch.h      |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/librte_eal/common/include/arch/ppc_64/rte_prefetch.h b/lib/librte_eal/common/include/arch/ppc_64/rte_prefetch.h
index bcc7185..9a1995e 100644
--- a/lib/librte_eal/common/include/arch/ppc_64/rte_prefetch.h
+++ b/lib/librte_eal/common/include/arch/ppc_64/rte_prefetch.h
@@ -41,17 +41,17 @@ extern "C" {
 
 static inline void rte_prefetch0(const volatile void *p)
 {
-	asm volatile ("dcbt 0,%[p],1" : : [p] "r" (p));
+	asm volatile ("dcbt 0,%[p],0" : : [p] "r" (p));
 }
 
 static inline void rte_prefetch1(const volatile void *p)
 {
-	asm volatile ("dcbt 0,%[p],1" : : [p] "r" (p));
+	asm volatile ("dcbt 0,%[p],0" : : [p] "r" (p));
 }
 
 static inline void rte_prefetch2(const volatile void *p)
 {
-	asm volatile ("dcbt 0,%[p],1" : : [p] "r" (p));
+	asm volatile ("dcbt 0,%[p],0" : : [p] "r" (p));
 }
 
 static inline void rte_prefetch_non_temporal(const volatile void *p)
-- 
1.7.1



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