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[PATCH v3 3/3] migration/ram: Optimize ram_save_host_page()
From: |
Kunkun Jiang |
Subject: |
[PATCH v3 3/3] migration/ram: Optimize ram_save_host_page() |
Date: |
Fri, 5 Mar 2021 15:50:35 +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 | 39 +++++++++++++++++++--------------------
1 file changed, 19 insertions(+), 20 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index 9fc5b2997c..28215aefe4 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1991,6 +1991,8 @@ static int ram_save_host_page(RAMState *rs,
PageSearchStatus *pss,
int 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;
@@ -2003,30 +2005,27 @@ static int ram_save_host_page(RAMState *rs,
PageSearchStatus *pss,
int pages_this_iteration = 0;
/* Check if the page is dirty and send it if it is */
- if (!migration_bitmap_clear_dirty(rs, pss->block, pss->page)) {
- pss->page++;
- continue;
- }
-
- pages_this_iteration = ram_save_target_page(rs, pss, last_stage);
- if (pages_this_iteration < 0) {
- return pages_this_iteration;
- }
+ if (migration_bitmap_clear_dirty(rs, pss->block, pss->page)) {
+ pages_this_iteration = ram_save_target_page(rs, pss, last_stage);
+ if (pages_this_iteration < 0) {
+ return pages_this_iteration;
+ }
- pages += pages_this_iteration;
- pss->page++;
- /*
- * Allow rate limiting to happen in the middle of huge pages if
- * something is sent in the current iteration.
- */
- if (pagesize_bits > 1 && pages_this_iteration > 0) {
- migration_rate_limit();
+ pages += pages_this_iteration;
+ /*
+ * Allow rate limiting to happen in the middle of huge pages if
+ * something is sent in the current iteration.
+ */
+ if (pagesize_bits > 1 && pages_this_iteration > 0) {
+ migration_rate_limit();
+ }
}
- } while ((pss->page & (pagesize_bits - 1)) &&
+ pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page);
+ } 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
- Re: [PATCH v3 1/3] migration/ram: Modify the code comment of ram_save_host_page(), (continued)
[PATCH v3 2/3] migration/ram: Reduce unnecessary rate limiting, Kunkun Jiang, 2021/03/05
- Re: [PATCH v3 2/3] migration/ram: Reduce unnecessary rate limiting, Peter Xu, 2021/03/05
- Re: [PATCH v3 2/3] migration/ram: Reduce unnecessary rate limiting, Kunkun Jiang, 2021/03/08
- Re: [PATCH v3 2/3] migration/ram: Reduce unnecessary rate limiting, Peter Xu, 2021/03/08
- Re: [PATCH v3 2/3] migration/ram: Reduce unnecessary rate limiting, Kunkun Jiang, 2021/03/09
- Re: [PATCH v3 2/3] migration/ram: Reduce unnecessary rate limiting, Peter Xu, 2021/03/09
- Re: [PATCH v3 2/3] migration/ram: Reduce unnecessary rate limiting, Kunkun Jiang, 2021/03/09
[PATCH v3 3/3] migration/ram: Optimize ram_save_host_page(),
Kunkun Jiang <=