on incoming migration do not memset pages to zero if they already read as zero.
this will allocate a new zero page and consume memory unnecessarily. even
if we madvise a MADV_DONTNEED later this will only deallocate the memory
asynchronously.
Signed-off-by: Peter Lieven <p...@kamp.de>
---
arch_init.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/arch_init.c b/arch_init.c
index 08fccf6..cf4e1d5 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -832,14 +832,16 @@ static int ram_load(QEMUFile *f, void *opaque, int
version_id)
}
ch = qemu_get_byte(f);
- memset(host, ch, TARGET_PAGE_SIZE);
+ if (ch != 0 || !is_zero_page(host)) {
+ memset(host, ch, TARGET_PAGE_SIZE);
#ifndef _WIN32
- if (ch == 0 &&
- (!kvm_enabled() || kvm_has_sync_mmu()) &&
- getpagesize() <= TARGET_PAGE_SIZE) {
- qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);
- }
+ if (ch == 0 &&
+ (!kvm_enabled() || kvm_has_sync_mmu()) &&
+ getpagesize() <= TARGET_PAGE_SIZE) {
+ qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);
+ }
#endif
+ }
} else if (flags & RAM_SAVE_FLAG_PAGE) {
void *host;
--
1.7.9.5
