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ARC: perf: avoid vmalloc backed mmap 

For non-alising Dcache, vmalloc is not needed.

vmalloc triggers additonal D-TLB Misses in the perf interrupt code path
making it slightly inefficient as evident from hackbench runs below.

| [ARCLinux]# perf stat -e dTLB-load-misses --repeat 5 hackbench
| Running with 10*40 (== 400) tasks.
| Time: 35.060
| ...
| Performance counter stats for 'hackbench' (5 runs):

Before:      399235      dTLB-load-misses ( +-  2.08% )
After :      397676      dTLB-load-misses ( +-  2.27% )

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2016-09-28 11:53:17 -07:00
parent 5b9027d6d0
commit 82385732b1
1 changed files with 1 additions and 1 deletions
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2
arch/arc/Kconfig
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@ -39,7 +39,7 @@ config ARC
select OF select OF
select OF_EARLY_FLATTREE select OF_EARLY_FLATTREE
select OF_RESERVED_MEM select OF_RESERVED_MEM
select PERF_USE_VMALLOC select PERF_USE_VMALLOC if ARC_CACHE_VIPT_ALIASING
select HAVE_DEBUG_STACKOVERFLOW select HAVE_DEBUG_STACKOVERFLOW
select HAVE_GENERIC_DMA_COHERENT select HAVE_GENERIC_DMA_COHERENT
select HAVE_KERNEL_GZIP select HAVE_KERNEL_GZIP