From 7c48005036a09142a662487ac52000ab845a07e8 Mon Sep 17 00:00:00 2001 From: Laurentiu Tudor Date: Fri, 30 May 2014 17:59:15 +0300 Subject: [PATCH] powerpc/booke64: wrap tlb lock and search in htw miss with FTR_SMT Virtualized environments may expose a e6500 dual-threaded core as two single-threaded e6500 cores. Take advantage of this and get rid of the tlb lock and the trap-causing tlbsx in the htw miss handler by guarding with CPU_FTR_SMT, as it's already being done in the bolted tlb1 miss handler. As seen in the results below, measurements done with lmbench random memory access latency test running under Freescale's Embedded Hypervisor, there is a ~34% improvement. Memory latencies in nanoseconds - smaller is better (WARNING - may not be correct, check graphs) ---------------------------------------------------- Host Mhz L1 $ L2 $ Main mem Rand mem --------- --- ---- ---- -------- -------- smt 1665 1.8020 13.2 83.0 1149.7 nosmt 1665 1.8020 13.2 83.0 758.1 Signed-off-by: Laurentiu Tudor Cc: Scott Wood [scottwood@freescale.com: commit message tweak] Signed-off-by: Scott Wood --- arch/powerpc/mm/tlb_low_64e.S | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/powerpc/mm/tlb_low_64e.S b/arch/powerpc/mm/tlb_low_64e.S index 131f1f4..57c4d66 100644 --- a/arch/powerpc/mm/tlb_low_64e.S +++ b/arch/powerpc/mm/tlb_low_64e.S @@ -299,6 +299,7 @@ itlb_miss_fault_bolted: * r10 = crap (free to use) */ tlb_miss_common_e6500: +BEGIN_FTR_SECTION /* * Search if we already have an indirect entry for that virtual * address, and if we do, bail out. @@ -333,6 +334,7 @@ tlb_miss_common_e6500: andis. r10,r10,MAS1_VALID@h bne tlb_miss_done_e6500 +END_FTR_SECTION_IFSET(CPU_FTR_SMT) /* Now, we need to walk the page tables. First check if we are in * range. @@ -393,11 +395,13 @@ tlb_miss_common_e6500: tlb_miss_done_e6500: .macro tlb_unlock_e6500 +BEGIN_FTR_SECTION beq cr1,1f /* no unlock if lock was recursively grabbed */ li r15,0 isync stb r15,0(r11) 1: +END_FTR_SECTION_IFSET(CPU_FTR_SMT) .endm tlb_unlock_e6500 -- 2.7.4