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[Qemu-devel] [PATCHv3 7/9] migration: do not sent zero pages in bulk sta
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCHv3 7/9] migration: do not sent zero pages in bulk stage |
Date: |
Thu, 21 Mar 2013 16:57:35 +0100 |
during bulk stage of ram migration if a page is a
zero page do not send it at all.
the memory at the destination reads as zero anyway.
even if there is an madvise with QEMU_MADV_DONTNEED
at the target upon receipt of a zero page I have observed
that the target starts swapping if the memory is overcommitted.
it seems that the pages are dropped asynchronously.
Signed-off-by: Peter Lieven <address@hidden>
---
arch_init.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch_init.c b/arch_init.c
index 2b59454..c2cb40a 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -438,10 +438,12 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
bytes_sent = -1;
if (is_zero_page(p)) {
acct_info.dup_pages++;
- bytes_sent = save_block_hdr(f, block, offset, cont,
- RAM_SAVE_FLAG_COMPRESS);
- qemu_put_byte(f, *p);
- bytes_sent += 1;
+ if (!ram_bulk_stage) {
+ bytes_sent = save_block_hdr(f, block, offset, cont,
+ RAM_SAVE_FLAG_COMPRESS);
+ qemu_put_byte(f, 0);
+ }
+ bytes_sent++;
} else if (migrate_use_xbzrle()) {
current_addr = block->offset + offset;
bytes_sent = save_xbzrle_page(f, p, current_addr, block,
--
1.7.9.5
- [Qemu-devel] [PATCHv3 0/9] buffer_is_zero / migration optimizations, Peter Lieven, 2013/03/21
- [Qemu-devel] [PATCHv3 1/9] move vector definitions to qemu-common.h, Peter Lieven, 2013/03/21
- [Qemu-devel] [PATCHv3 4/9] bitops: use vector algorithm to optimize find_next_bit(), Peter Lieven, 2013/03/21
- [Qemu-devel] [PATCHv3 8/9] migration: do not search dirty pages in bulk stage, Peter Lieven, 2013/03/21
- [Qemu-devel] [PATCHv3 7/9] migration: do not sent zero pages in bulk stage,
Peter Lieven <=
- [Qemu-devel] [PATCHv3 2/9] cutils: add a function to find non-zero content in a buffer, Peter Lieven, 2013/03/21
- [Qemu-devel] [PATCHv3 9/9] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/21
- [Qemu-devel] [PATCHv3 5/9] migration: search for zero instead of dup pages, Peter Lieven, 2013/03/21
- [Qemu-devel] [PATCHv3 6/9] migration: add an indicator for bulk state of ram migration, Peter Lieven, 2013/03/21