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[Qemu-devel] [PULL 20/33] migration/postcopy: simplify calculation of ru
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [PULL 20/33] migration/postcopy: simplify calculation of run_start and fixup_start_addr |
Date: |
Thu, 15 Aug 2019 17:34:51 +0100 |
From: Wei Yang <address@hidden>
The purpose of the calculation is to find a HostPage which is partially
dirty.
* fixup_start_addr points to the start of the HostPage to discard
* run_start points to the next HostPage to check
While in the middle stage, there would two cases for run_start:
* aligned with HostPage means this is not partially dirty
* not aligned means this is partially dirty
When it is aligned, no work and calculation is necessary. run_start
already points to the start of next HostPage and is ready to continue.
When it is not aligned, the calculation could be simplified with:
* fixup_start_addr = QEMU_ALIGN_DOWN(run_start, host_ratio)
* run_start = QEMU_ALIGN_UP(run_start, host_ratio)
By doing so, run_start always points to the next HostPage to check.
fixup_start_addr always points to the HostPage to discard.
Signed-off-by: Wei Yang <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
migration/ram.c | 34 +++++++---------------------------
1 file changed, 7 insertions(+), 27 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index f428639af5..d2184c3cfc 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2955,7 +2955,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState
*ms, bool unsent_pass,
}
while (run_start < pages) {
- unsigned long fixup_start_addr;
unsigned long host_offset;
/*
@@ -2963,45 +2962,26 @@ static void
postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
* page, then we need to fixup this host page.
*/
host_offset = run_start % host_ratio;
- if (host_offset) {
- fixup_start_addr = run_start - host_offset;
- /*
- * This host page has gone, the next loop iteration starts
- * from after the fixup
- */
- run_start = fixup_start_addr + host_ratio;
- } else {
+ if (!host_offset) {
/* Find the end of this run */
- unsigned long run_end;
if (unsent_pass) {
- run_end = find_next_bit(unsentmap, pages, run_start + 1);
+ run_start = find_next_bit(unsentmap, pages, run_start + 1);
} else {
- run_end = find_next_zero_bit(bitmap, pages, run_start + 1);
+ run_start = find_next_zero_bit(bitmap, pages, run_start + 1);
}
/*
* If the end isn't at the start of a host page, then the
* run doesn't finish at the end of a host page
* and we need to discard.
*/
- host_offset = run_end % host_ratio;
- if (host_offset) {
- fixup_start_addr = run_end - host_offset;
- /*
- * This host page has gone, the next loop iteration starts
- * from after the fixup
- */
- run_start = fixup_start_addr + host_ratio;
- } else {
- /*
- * No discards on this iteration, next loop starts from
- * next sent/dirty page
- */
- run_start = run_end + 1;
- }
+ host_offset = run_start % host_ratio;
}
if (host_offset) {
unsigned long page;
+ unsigned long fixup_start_addr = QEMU_ALIGN_DOWN(run_start,
+ host_ratio);
+ run_start = QEMU_ALIGN_UP(run_start, host_ratio);
/* Tell the destination to discard this page */
if (unsent_pass || !test_bit(fixup_start_addr, unsentmap)) {
--
2.21.0
- [Qemu-devel] [PULL 10/33] migration/savevm: split qemu_savevm_state_complete_precopy() into two parts, (continued)
- [Qemu-devel] [PULL 10/33] migration/savevm: split qemu_savevm_state_complete_precopy() into two parts, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 11/33] migration/savevm: move non SaveStateEntry condition check out of iteration, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 12/33] migration/postcopy: PostcopyState is already set in loadvm_postcopy_handle_advise(), Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 13/33] migration/postcopy: start_postcopy could be true only when migrate_postcopy() return true, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 14/33] migration: use migration_in_postcopy() to check POSTCOPY_ACTIVE, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 15/33] migration: just pass RAMBlock is enough, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 17/33] migration: return -EINVAL directly when version_id mismatch, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 16/33] migration: equation is more proper than and to check LOADVM_QUIT, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 18/33] migration: extract ram_load_precopy, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 19/33] migration/postcopy: make PostcopyDiscardState a static variable, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 20/33] migration/postcopy: simplify calculation of run_start and fixup_start_addr,
Dr. David Alan Gilbert (git) <=
- [Qemu-devel] [PULL 21/33] migration/postcopy: use QEMU_IS_ALIGNED to replace host_offset, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 22/33] hmp: Remove migration capabilities from "info migrate", Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 23/33] migration: remove unused field bytes_xfer, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 24/33] migration: always initialise ram_counters for a new migration, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 25/33] migration: add qemu_file_update_transfer interface, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 26/33] migration: add speed limit for multifd migration, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 27/33] migration: update ram_counters for multifd sync packet, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 28/33] migration: rename migration_bitmap_sync_range to ramblock_sync_dirty_bitmap, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 30/33] qemu-file: move qemu_{get, put}_counted_string() declarations, Dr. David Alan Gilbert (git), 2019/08/15
- [Qemu-devel] [PULL 29/33] migration/postcopy: use mis->bh instead of allocating a QEMUBH, Dr. David Alan Gilbert (git), 2019/08/15