Commit 7069532e authored Jul 14, 2016 by Vijay Committed by Peter Maydell Jul 14, 2016

target-arm: Use Neon for zero checking



Use Neon instructions to perform zero checking of
buffer. This is helps in reducing total migration time.

Use case: Idle VM live migration with 4 VCPUS and 8GB ram
running CentOS 7.

Without Neon, the Total migration time is 3.5 Sec

Migration status: completed
total time: 3560 milliseconds
downtime: 33 milliseconds
setup: 5 milliseconds
transferred ram: 297907 kbytes
throughput: 685.76 mbps
remaining ram: 0 kbytes
total ram: 8519872 kbytes
duplicate: 2062760 pages
skipped: 0 pages
normal: 69808 pages
normal bytes: 279232 kbytes
dirty sync count: 3

With Neon, the total migration time is 2.9 Sec

Migration status: completed
total time: 2960 milliseconds
downtime: 65 milliseconds
setup: 4 milliseconds
transferred ram: 299869 kbytes
throughput: 830.19 mbps
remaining ram: 0 kbytes
total ram: 8519872 kbytes
duplicate: 2064313 pages
skipped: 0 pages
normal: 70294 pages
normal bytes: 281176 kbytes
dirty sync count: 3

Signed-off-by: Vijaya Kumar K <vijayak@cavium.com>
Signed-off-by: Suresh <ksuresh@cavium.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1467190029-694-2-git-send-email-vijayak@cavium.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

parent 56215da3

util/cutils.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -184,6 +184,13 @@ int qemu_fdatasync(int fd)
		#define SPLAT(p) _mm_set1_epi8(*(p))
		#define ALL_EQ(v1, v2) (_mm_movemask_epi8(_mm_cmpeq_epi8(v1, v2)) == 0xFFFF)
		#define VEC_OR(v1, v2) (_mm_or_si128(v1, v2))
		#elif defined(__aarch64__)
		#include "arm_neon.h"
		#define VECTYPE uint64x2_t
		#define ALL_EQ(v1, v2) \
		((vgetq_lane_u64(v1, 0) == vgetq_lane_u64(v2, 0)) && \
		(vgetq_lane_u64(v1, 1) == vgetq_lane_u64(v2, 1)))
		#define VEC_OR(v1, v2) ((v1) \| (v2))
		#else
		#define VECTYPE unsigned long
		#define SPLAT(p) ((p) (~0UL / 255))