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authorAdhemerval Zanella <azanella@linux.vnet.ibm.com>2014-12-31 11:47:41 -0500
committerAdhemerval Zanella <azanella@linux.vnet.ibm.com>2015-01-13 11:28:44 -0500
commitf06a4faf8a2b4d046eb40e94b47948cc47d79902 (patch)
tree846d1fc4c0ce0be53ef275c227b2accab263bbda /NEWS
parent9f2f36e5a91c2ce6edba5415e176155eb1008ae1 (diff)
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powerpc: Optimized st{r,p}ncpy for POWER8/PPC64
This patch adds an optimized POWER8 st{r,p}ncpy using unaligned accesses.
It shows 10%-80% improvement over the optimized POWER7 one that uses
only aligned accesses, specially on unaligned inputs.

The algorithm first read and check 16 bytes (if inputs do not cross a 4K
page size).  The it realign source to 16-bytes and issue a 16 bytes read
and compare loop to speedup null byte checks for large strings.  Also,
different from POWER7 optimization, the null pad is done inline in the
implementation using possible unaligned accesses, instead of realying on
a memset call.  Special case is added for page cross reads.
Diffstat (limited to 'NEWS')
-rw-r--r--NEWS3
1 files changed, 2 insertions, 1 deletions
diff --git a/NEWS b/NEWS
index e02091802e..08b3daacd5 100644
--- a/NEWS
+++ b/NEWS
@@ -19,7 +19,8 @@ Version 2.21
   17744, 17745, 17746, 17747, 17748, 17775, 17777, 17780, 17781, 17782,
   17791, 17793, 17796, 17797, 17803, 17806, 17834
 
-* Optimized strcpy and stpcpy implementations for powerpc64/powerpc64le.
+* Optimized strcpy, stpcpy, strncpy, stpncpy implementations for
+  powerpc64/powerpc64le.
 
 * Added support for TSX lock elision of pthread mutexes on powerpc32, powerpc64
   and powerpc64le.  This may improve lock scaling of existing programs on