Re: [PATCH 3/5] Migration thread mutex
On Sat, Aug 27, 2011 at 7:09 PM, Umesh Deshpande udesh...@redhat.com wrote:
This patch implements migrate_ram mutex, which protects the RAMBlock list
traversal in the migration thread during the transfer of a ram from their
addition/removal from the iothread.
Note: Combination of iothread mutex and migration thread mutex works as a
rw-lock. Both mutexes are acquired while modifying the ram_list members or RAM
block list.
Signed-off-by: Umesh Deshpande udesh...@redhat.com
---
arch_init.c | 21 +
cpu-all.h | 3 +++
exec.c | 23 +++
qemu-common.h | 2 ++
4 files changed, 49 insertions(+), 0 deletions(-)
diff --git a/arch_init.c b/arch_init.c
index 484b39d..9d02270 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -109,6 +109,7 @@ static int is_dup_page(uint8_t *page, uint8_t ch)
static RAMBlock *last_block;
static ram_addr_t last_offset;
+static uint64_t last_version;
[...]
typedef struct RAMList {
+ QemuMutex mutex; /* Protects RAM block list */
uint8_t *phys_dirty;
+ uint32_t version; /* To detect ram block addition/removal */
Is there a reason why RAMList.version is uint32_t but last_version is uint64_t?
Stefan
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Re: [PATCH 3/5] Migration thread mutex
On 08/29/2011 05:04 AM, Stefan Hajnoczi wrote:
On Sat, Aug 27, 2011 at 7:09 PM, Umesh Deshpandeudesh...@redhat.com wrote:
This patch implements migrate_ram mutex, which protects the RAMBlock list
traversal in the migration thread during the transfer of a ram from their
addition/removal from the iothread.
Note: Combination of iothread mutex and migration thread mutex works as a
rw-lock. Both mutexes are acquired while modifying the ram_list members or RAM
block list.
Signed-off-by: Umesh Deshpandeudesh...@redhat.com
---
arch_init.c | 21 +
cpu-all.h |3 +++
exec.c| 23 +++
qemu-common.h |2 ++
4 files changed, 49 insertions(+), 0 deletions(-)
diff --git a/arch_init.c b/arch_init.c
index 484b39d..9d02270 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -109,6 +109,7 @@ static int is_dup_page(uint8_t *page, uint8_t ch)
static RAMBlock *last_block;
static ram_addr_t last_offset;
+static uint64_t last_version;
[...]
typedef struct RAMList {
+QemuMutex mutex;/* Protects RAM block list */
uint8_t *phys_dirty;
+uint32_t version; /* To detect ram block addition/removal */
Is there a reason why RAMList.version is uint32_t but last_version is uint64_t?
No, my bad, they both should be consistent.
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Re: [PATCH 3/5] Migration thread mutex
On Sat, Aug 27, 2011 at 02:09:46PM -0400, Umesh Deshpande wrote:
This patch implements migrate_ram mutex, which protects the RAMBlock list
traversal in the migration thread during the transfer of a ram from their
addition/removal from the iothread.
Note: Combination of iothread mutex and migration thread mutex works as a
rw-lock. Both mutexes are acquired while modifying the ram_list members or RAM
block list.
Signed-off-by: Umesh Deshpande udesh...@redhat.com
---
arch_init.c | 21 +
cpu-all.h |3 +++
exec.c| 23 +++
qemu-common.h |2 ++
4 files changed, 49 insertions(+), 0 deletions(-)
diff --git a/arch_init.c b/arch_init.c
index 484b39d..9d02270 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -109,6 +109,7 @@ static int is_dup_page(uint8_t *page, uint8_t ch)
static RAMBlock *last_block;
static ram_addr_t last_offset;
+static uint64_t last_version;
static int ram_save_block(QEMUFile *f)
{
@@ -170,6 +171,7 @@ static int ram_save_block(QEMUFile *f)
last_block = block;
last_offset = offset;
+last_version = ram_list.version;
return bytes_sent;
}
@@ -270,6 +272,7 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage,
void *opaque)
bytes_transferred = 0;
last_block = NULL;
last_offset = 0;
+last_version = ram_list.version = 0;
sort_ram_list();
/* Make sure all dirty bits are set */
@@ -298,6 +301,17 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage,
void *opaque)
bytes_transferred_last = bytes_transferred;
bwidth = qemu_get_clock_ns(rt_clock);
+if (stage != 3) {
+qemu_mutex_lock_migrate_ram();
+qemu_mutex_unlock_iothread();
+}
Dropping the iothread lock from within a timer handler is not safe.
This change to ram_save_live should be moved to the patch where
migration thread is introduced.
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