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[Qemu-devel] [PATCH v3 20/32] migration: synchronize dirty bitmap for re
From: |
Peter Xu |
Subject: |
[Qemu-devel] [PATCH v3 20/32] migration: synchronize dirty bitmap for resume |
Date: |
Mon, 16 Oct 2017 14:52:04 +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.
Signed-off-by: Peter Xu <address@hidden>
---
migration/migration.c | 4 ++++
migration/migration.h | 1 +
migration/ram.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
migration/trace-events | 4 ++++
4 files changed, 56 insertions(+)
diff --git a/migration/migration.c b/migration/migration.c
index 3762e69eb3..52f81c3add 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2739,6 +2739,8 @@ static void migration_instance_finalize(Object *obj)
g_free(params->tls_hostname);
g_free(params->tls_creds);
+
+ qemu_sem_destroy(&ms->rp_state.rp_sem);
}
static void migration_instance_init(Object *obj)
@@ -2765,6 +2767,8 @@ static void migration_instance_init(Object *obj)
params->has_block_incremental = true;
params->has_x_multifd_channels = true;
params->has_x_multifd_page_count = true;
+
+ qemu_sem_init(&ms->rp_state.rp_sem, 0);
}
/*
diff --git a/migration/migration.h b/migration/migration.h
index feeb1997a2..c8d5939d43 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -108,6 +108,7 @@ 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 fa2b4ed207..a7431a802e 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -48,6 +48,7 @@
#include "qemu/rcu_queue.h"
#include "migration/colo.h"
#include "migration/block.h"
+#include "savevm.h"
/***********************************************************/
/* ram save/restore */
@@ -2984,6 +2985,38 @@ 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
@@ -3058,12 +3091,25 @@ 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,
@@ -3075,6 +3121,7 @@ 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 eadabf03e8..804f18d492 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) ""
--
2.13.5
- [Qemu-devel] [PATCH v3 10/32] qmp: hmp: add migrate "resume" option, (continued)
- [Qemu-devel] [PATCH v3 10/32] qmp: hmp: add migrate "resume" option, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 11/32] migration: pass MigrationState to migrate_init(), Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 12/32] migration: rebuild channel on source, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 13/32] migration: new state "postcopy-recover", Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 14/32] migration: wakeup dst ram-load-thread for recover, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 15/32] migration: new cmd MIG_CMD_RECV_BITMAP, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 16/32] migration: new message MIG_RP_MSG_RECV_BITMAP, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 17/32] migration: new cmd MIG_CMD_POSTCOPY_RESUME, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 18/32] migration: new message MIG_RP_MSG_RESUME_ACK, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 19/32] migration: introduce SaveVMHandlers.resume_prepare, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 20/32] migration: synchronize dirty bitmap for resume,
Peter Xu <=
- [Qemu-devel] [PATCH v3 21/32] migration: setup ramstate for resume, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 22/32] migration: final handshake for the resume, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 23/32] migration: free SocketAddress where allocated, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 24/32] migration: return incoming task tag for sockets, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 25/32] migration: return incoming task tag for exec, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 26/32] migration: return incoming task tag for fd, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 27/32] migration: store listen task tag, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 28/32] migration: allow migrate_incoming for paused VM, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 29/32] migration: init dst in migration_object_init too, Peter Xu, 2017/10/16
- [Qemu-devel] [PATCH v3 30/32] migration: delay the postcopy-active state switch, Peter Xu, 2017/10/16