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[Qemu-devel] [PATCH 22/22] migration: run bitmap sync outside iothread l
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 22/22] migration: run bitmap sync outside iothread lock |
Date: |
Thu, 26 Mar 2015 18:38:40 +0100 |
Synchronization of the dirty bitmap can now run concurrently
with modifications of it.
Note that the change in migration_bitmap_sync is not needed
and is only for improved clarity.
Signed-off-by: Paolo Bonzini <address@hidden>
---
arch_init.c | 10 +++++-----
include/exec/memory.h | 8 ++++++++
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/arch_init.c b/arch_init.c
index 75bba49..3ac63c6 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -512,10 +512,10 @@ static void migration_bitmap_sync(void)
start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
}
+ rcu_read_lock();
trace_migration_bitmap_sync_start();
address_space_sync_dirty_bitmap(&address_space_memory);
- rcu_read_lock();
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
migration_bitmap_sync_range(block->mr->ram_addr, block->used_length);
}
@@ -838,7 +838,9 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
acct_clear();
}
- /* iothread lock needed for ram_list.dirty_memory[] */
+ /* iothread lock needed for ram_list.dirty_memory[],
+ * ramlist lock needed for memory_global_dirty_log_start().
+ */
qemu_mutex_lock_iothread();
qemu_mutex_lock_ramlist();
rcu_read_lock();
@@ -856,10 +858,10 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
memory_global_dirty_log_start();
- migration_bitmap_sync();
qemu_mutex_unlock_ramlist();
qemu_mutex_unlock_iothread();
+ migration_bitmap_sync();
qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE);
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
@@ -980,11 +982,9 @@ static uint64_t ram_save_pending(QEMUFile *f, void
*opaque, uint64_t max_size)
remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE;
if (remaining_size < max_size) {
- qemu_mutex_lock_iothread();
rcu_read_lock();
migration_bitmap_sync();
rcu_read_unlock();
- qemu_mutex_unlock_iothread();
remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE;
}
return remaining_size;
diff --git a/include/exec/memory.h b/include/exec/memory.h
index aa46a52..e79e2d5 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -177,6 +177,9 @@ struct MemoryRegion {
*
* Allows a component to adjust to changes in the guest-visible memory map.
* Use with memory_listener_register() and memory_listener_unregister().
+ *
+ * All functions called while holding the iothread lock, EXCEPT FOR log_sync
+ * which may be called either with or without the iothread lock held.
*/
struct MemoryListener {
void (*begin)(MemoryListener *listener);
@@ -682,6 +685,9 @@ bool memory_region_test_and_clear_dirty(MemoryRegion *mr,
hwaddr addr,
* Flushes dirty information from accelerators such as kvm and vhost-net
* and makes it available to users of the memory API.
*
+ * Unlike other memory region function, memory_region_sync_dirty_bitmap
+ * may be called either with or without the iothread lock held.
+ *
* @mr: the region being flushed.
*/
void memory_region_sync_dirty_bitmap(MemoryRegion *mr);
@@ -994,6 +1000,8 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr,
* address_space_sync_dirty_bitmap: synchronize the dirty log for all memory
*
* Synchronizes the dirty page log for an entire address space.
+ * May be called either with or without the iothread lock held.
+ *
* @as: the address space that contains the memory being synchronized
*/
void address_space_sync_dirty_bitmap(AddressSpace *as);
--
2.3.3
- [Qemu-devel] [PATCH 13/22] exec: pass client mask to cpu_physical_memory_set_dirty_range, (continued)
- [Qemu-devel] [PATCH 13/22] exec: pass client mask to cpu_physical_memory_set_dirty_range, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 11/22] exec: simplify notdirty_mem_write, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 14/22] exec: only check relevant bitmaps for cleanliness, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 15/22] memory: do not touch code dirty bitmap unless TCG is enabled, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 17/22] bitmap: add atomic test and clear, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 18/22] memory: use atomic ops for setting dirty memory bits, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 16/22] bitmap: add atomic set functions, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 19/22] migration: move dirty bitmap sync to ram_addr.h, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 21/22] memory: make cpu_physical_memory_sync_dirty_bitmap() fully atomic, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 20/22] memory: replace cpu_physical_memory_reset_dirty() with test-and-clear, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 22/22] migration: run bitmap sync outside iothread lock,
Paolo Bonzini <=