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[PATCH v2 3/3] migration/ram: Optimize ram_save_host_page()
From: |
Kunkun Jiang |
Subject: |
[PATCH v2 3/3] migration/ram: Optimize ram_save_host_page() |
Date: |
Mon, 1 Mar 2021 16:21:32 +0800 |
Starting from pss->page, ram_save_host_page() will check every page
and send the dirty pages up to the end of the current host page or
the boundary of used_length of the block. If the host page size is
a huge page, the step "check" will take a lot of time.
This will improve performance to use migration_bitmap_find_dirty().
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
---
migration/ram.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index 3a9115b6dc..a1374db356 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1991,6 +1991,8 @@ static int ram_save_host_page(RAMState *rs,
PageSearchStatus *pss,
int tmppages, pages = 0;
size_t pagesize_bits =
qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS;
+ unsigned long hostpage_boundary =
+ QEMU_ALIGN_UP(pss->page + 1, pagesize_bits);
unsigned long start_page = pss->page;
int res;
@@ -2002,7 +2004,7 @@ static int ram_save_host_page(RAMState *rs,
PageSearchStatus *pss,
do {
/* Check the pages is dirty and if it is send it */
if (!migration_bitmap_clear_dirty(rs, pss->block, pss->page)) {
- pss->page++;
+ pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page);
continue;
}
@@ -2012,16 +2014,16 @@ static int ram_save_host_page(RAMState *rs,
PageSearchStatus *pss,
}
pages += tmppages;
- pss->page++;
+ pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page);
/* Allow rate limiting to happen in the middle of huge pages */
if (pagesize_bits > 1) {
migration_rate_limit();
}
- } while ((pss->page & (pagesize_bits - 1)) &&
+ } while ((pss->page < hostpage_boundary) &&
offset_in_ramblock(pss->block,
((ram_addr_t)pss->page) << TARGET_PAGE_BITS));
- /* The offset we leave with is the last one we looked at */
- pss->page--;
+ /* The offset we leave with is the min boundary of host page and block */
+ pss->page = MIN(pss->page, hostpage_boundary) - 1;
res = ram_save_release_protection(rs, pss, start_page);
return (res < 0 ? res : pages);
--
2.23.0