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[Qemu-devel] [PATCH v7 16/23] migration: synchronize dirty bitmap for re
From: |
Peter Xu |
Subject: |
[Qemu-devel] [PATCH v7 16/23] migration: synchronize dirty bitmap for resume |
Date: |
Fri, 9 Mar 2018 17:15:28 +0800 |
This patch implements the first part of core RAM resume logic for
postcopy. ram_resume_prepare() is provided for the work.
When the migration is interrupted by network failure, the dirty bitmap
on the source side will be meaningless, because even the dirty bit is
cleared, it is still possible that the sent page was lost along the way
to destination. Here instead of continue the migration with the old
dirty bitmap on source, we ask the destination side to send back its
received bitmap, then invert it to be our initial dirty bitmap.
The source side send thread will issue the MIG_CMD_RECV_BITMAP requests,
once per ramblock, to ask for the received bitmap. On destination side,
MIG_RP_MSG_RECV_BITMAP will be issued, along with the requested bitmap.
Data will be received on the return-path thread of source, and the main
migration thread will be notified when all the ramblock bitmaps are
synchronized.
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
Signed-off-by: Peter Xu <address@hidden>
---
migration/migration.c | 2 ++
migration/migration.h | 1 +
migration/ram.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
migration/trace-events | 4 ++++
4 files changed, 54 insertions(+)
diff --git a/migration/migration.c b/migration/migration.c
index a2b98afb4d..71e4195422 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2896,6 +2896,7 @@ static void migration_instance_finalize(Object *obj)
qemu_sem_destroy(&ms->pause_sem);
qemu_sem_destroy(&ms->postcopy_pause_sem);
qemu_sem_destroy(&ms->postcopy_pause_rp_sem);
+ qemu_sem_destroy(&ms->rp_state.rp_sem);
}
static void migration_instance_init(Object *obj)
@@ -2927,6 +2928,7 @@ static void migration_instance_init(Object *obj)
qemu_sem_init(&ms->postcopy_pause_sem, 0);
qemu_sem_init(&ms->postcopy_pause_rp_sem, 0);
+ qemu_sem_init(&ms->rp_state.rp_sem, 0);
}
/*
diff --git a/migration/migration.h b/migration/migration.h
index dca16307c2..8f64b43584 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -119,6 +119,7 @@ struct MigrationState
QEMUFile *from_dst_file;
QemuThread rp_thread;
bool error;
+ QemuSemaphore rp_sem;
} rp_state;
double mbps;
diff --git a/migration/ram.c b/migration/ram.c
index a897c250cb..196b1ba876 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -51,6 +51,7 @@
#include "qemu/rcu_queue.h"
#include "migration/colo.h"
#include "migration/block.h"
+#include "savevm.h"
/***********************************************************/
/* ram save/restore */
@@ -3060,6 +3061,38 @@ static bool ram_has_postcopy(void *opaque)
return migrate_postcopy_ram();
}
+/* Sync all the dirty bitmap with destination VM. */
+static int ram_dirty_bitmap_sync_all(MigrationState *s, RAMState *rs)
+{
+ RAMBlock *block;
+ QEMUFile *file = s->to_dst_file;
+ int ramblock_count = 0;
+
+ trace_ram_dirty_bitmap_sync_start();
+
+ RAMBLOCK_FOREACH(block) {
+ qemu_savevm_send_recv_bitmap(file, block->idstr);
+ trace_ram_dirty_bitmap_request(block->idstr);
+ ramblock_count++;
+ }
+
+ trace_ram_dirty_bitmap_sync_wait();
+
+ /* Wait until all the ramblocks' dirty bitmap synced */
+ while (ramblock_count--) {
+ qemu_sem_wait(&s->rp_state.rp_sem);
+ }
+
+ trace_ram_dirty_bitmap_sync_complete();
+
+ return 0;
+}
+
+static void ram_dirty_bitmap_reload_notify(MigrationState *s)
+{
+ qemu_sem_post(&s->rp_state.rp_sem);
+}
+
/*
* Read the received bitmap, revert it as the initial dirty bitmap.
* This is only used when the postcopy migration is paused but wants
@@ -3134,12 +3167,25 @@ int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock
*block)
trace_ram_dirty_bitmap_reload_complete(block->idstr);
+ /*
+ * We succeeded to sync bitmap for current ramblock. If this is
+ * the last one to sync, we need to notify the main send thread.
+ */
+ ram_dirty_bitmap_reload_notify(s);
+
ret = 0;
out:
free(le_bitmap);
return ret;
}
+static int ram_resume_prepare(MigrationState *s, void *opaque)
+{
+ RAMState *rs = *(RAMState **)opaque;
+
+ return ram_dirty_bitmap_sync_all(s, rs);
+}
+
static SaveVMHandlers savevm_ram_handlers = {
.save_setup = ram_save_setup,
.save_live_iterate = ram_save_iterate,
@@ -3151,6 +3197,7 @@ static SaveVMHandlers savevm_ram_handlers = {
.save_cleanup = ram_save_cleanup,
.load_setup = ram_load_setup,
.load_cleanup = ram_load_cleanup,
+ .resume_prepare = ram_resume_prepare,
};
void ram_mig_init(void)
diff --git a/migration/trace-events b/migration/trace-events
index fe46b2c6c5..45b1d89217 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -82,8 +82,12 @@ ram_load_postcopy_loop(uint64_t addr, int flags) "@%" PRIx64
" %x"
ram_postcopy_send_discard_bitmap(void) ""
ram_save_page(const char *rbname, uint64_t offset, void *host) "%s: offset:
0x%" PRIx64 " host: %p"
ram_save_queue_pages(const char *rbname, size_t start, size_t len) "%s: start:
0x%zx len: 0x%zx"
+ram_dirty_bitmap_request(char *str) "%s"
ram_dirty_bitmap_reload_begin(char *str) "%s"
ram_dirty_bitmap_reload_complete(char *str) "%s"
+ram_dirty_bitmap_sync_start(void) ""
+ram_dirty_bitmap_sync_wait(void) ""
+ram_dirty_bitmap_sync_complete(void) ""
# migration/migration.c
await_return_path_close_on_source_close(void) ""
--
2.14.3
- [Qemu-devel] [PATCH v7 06/23] migration: allow fault thread to pause, (continued)
- [Qemu-devel] [PATCH v7 06/23] migration: allow fault thread to pause, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 07/23] qmp: hmp: add migrate "resume" option, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 08/23] migration: rebuild channel on source, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 10/23] migration: wakeup dst ram-load-thread for recover, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 09/23] migration: new state "postcopy-recover", Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 11/23] migration: new cmd MIG_CMD_RECV_BITMAP, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 14/23] migration: new message MIG_RP_MSG_RESUME_ACK, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 12/23] migration: new message MIG_RP_MSG_RECV_BITMAP, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 13/23] migration: new cmd MIG_CMD_POSTCOPY_RESUME, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 15/23] migration: introduce SaveVMHandlers.resume_prepare, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 16/23] migration: synchronize dirty bitmap for resume,
Peter Xu <=
- [Qemu-devel] [PATCH v7 17/23] migration: setup ramstate for resume, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 18/23] migration: final handshake for the resume, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 19/23] migration: init dst in migration_object_init too, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 21/23] hmp/migration: add migrate_recover command, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 20/23] qmp/migration: new command migrate-recover, Peter Xu, 2018/03/09
- [Qemu-devel] [PATCH v7 22/23] migration/qmp: add command migrate-pause, Peter Xu, 2018/03/09