[2/4] block/aio_task: allow start/wait task from any coroutine
diff mbox series

Message ID 20200611171143.21589-3-den@openvz.org
State New
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Series
  • block: seriously improve savevm performance
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Commit Message

Denis V. Lunev June 11, 2020, 5:11 p.m. UTC
From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Currently, aio task pool assumes that there is a main coroutine, which
creates tasks and wait for them. Let's remove the restriction by using
CoQueue. Code becomes clearer, interface more obvious.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Fam Zheng <fam@euphon.net>
CC: Juan Quintela <quintela@redhat.com>
CC: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
CC: Denis Plotnikov <dplotnikov@virtuozzo.com>
---
 block/aio_task.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

Comments

Vladimir Sementsov-Ogievskiy June 15, 2020, 7:47 a.m. UTC | #1
11.06.2020 20:11, Denis V. Lunev wrote:
> From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> 
> Currently, aio task pool assumes that there is a main coroutine, which
> creates tasks and wait for them. Let's remove the restriction by using
> CoQueue. Code becomes clearer, interface more obvious.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Max Reitz <mreitz@redhat.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Fam Zheng <fam@euphon.net>
> CC: Juan Quintela <quintela@redhat.com>
> CC: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> CC: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> CC: Denis Plotnikov <dplotnikov@virtuozzo.com>
> ---
>   block/aio_task.c | 21 ++++++---------------
>   1 file changed, 6 insertions(+), 15 deletions(-)
> 
> diff --git a/block/aio_task.c b/block/aio_task.c
> index 88989fa248..cf62e5c58b 100644
> --- a/block/aio_task.c
> +++ b/block/aio_task.c
> @@ -27,11 +27,10 @@
>   #include "block/aio_task.h"
>   
>   struct AioTaskPool {
> -    Coroutine *main_co;
>       int status;
>       int max_busy_tasks;
>       int busy_tasks;
> -    bool waiting;
> +    CoQueue waiters;
>   };
>   
>   static void coroutine_fn aio_task_co(void *opaque)
> @@ -52,31 +51,23 @@ static void coroutine_fn aio_task_co(void *opaque)
>   
>       g_free(task);
>   
> -    if (pool->waiting) {
> -        pool->waiting = false;
> -        aio_co_wake(pool->main_co);
> -    }
> +    qemu_co_queue_restart_all(&pool->waiters);
>   }
>   
>   void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool)
>   {
>       assert(pool->busy_tasks > 0);
> -    assert(qemu_coroutine_self() == pool->main_co);
>   
> -    pool->waiting = true;
> -    qemu_coroutine_yield();
> +    qemu_co_queue_wait(&pool->waiters, NULL);
>   
> -    assert(!pool->waiting);
>       assert(pool->busy_tasks < pool->max_busy_tasks);

As we wake up several coroutines now, I'm afraid this assertion may start to fire.
And aio_task_pool_wait_one() becomes useless as a public API (still, it's used only locally, so we can make it static).

I'll send updated patch after reviewing the rest of the series.

>   }
>   
>   void coroutine_fn aio_task_pool_wait_slot(AioTaskPool *pool)
>   {
> -    if (pool->busy_tasks < pool->max_busy_tasks) {
> -        return;
> +    while (pool->busy_tasks >= pool->max_busy_tasks) {
> +        aio_task_pool_wait_one(pool);
>       }
> -
> -    aio_task_pool_wait_one(pool);
>   }
>   
>   void coroutine_fn aio_task_pool_wait_all(AioTaskPool *pool)
> @@ -98,8 +89,8 @@ AioTaskPool *coroutine_fn aio_task_pool_new(int max_busy_tasks)
>   {
>       AioTaskPool *pool = g_new0(AioTaskPool, 1);
>   
> -    pool->main_co = qemu_coroutine_self();
>       pool->max_busy_tasks = max_busy_tasks;
> +    qemu_co_queue_init(&pool->waiters);
>   
>       return pool;
>   }
>
Vladimir Sementsov-Ogievskiy June 15, 2020, 9:34 a.m. UTC | #2
15.06.2020 10:47, Vladimir Sementsov-Ogievskiy wrote:
> 11.06.2020 20:11, Denis V. Lunev wrote:
>> From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>
>> Currently, aio task pool assumes that there is a main coroutine, which
>> creates tasks and wait for them. Let's remove the restriction by using
>> CoQueue. Code becomes clearer, interface more obvious.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>> CC: Kevin Wolf <kwolf@redhat.com>
>> CC: Max Reitz <mreitz@redhat.com>
>> CC: Stefan Hajnoczi <stefanha@redhat.com>
>> CC: Fam Zheng <fam@euphon.net>
>> CC: Juan Quintela <quintela@redhat.com>
>> CC: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>> CC: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> CC: Denis Plotnikov <dplotnikov@virtuozzo.com>
>> ---
>>   block/aio_task.c | 21 ++++++---------------
>>   1 file changed, 6 insertions(+), 15 deletions(-)
>>
>> diff --git a/block/aio_task.c b/block/aio_task.c
>> index 88989fa248..cf62e5c58b 100644
>> --- a/block/aio_task.c
>> +++ b/block/aio_task.c
>> @@ -27,11 +27,10 @@
>>   #include "block/aio_task.h"
>>   struct AioTaskPool {
>> -    Coroutine *main_co;
>>       int status;
>>       int max_busy_tasks;
>>       int busy_tasks;
>> -    bool waiting;
>> +    CoQueue waiters;
>>   };
>>   static void coroutine_fn aio_task_co(void *opaque)
>> @@ -52,31 +51,23 @@ static void coroutine_fn aio_task_co(void *opaque)
>>       g_free(task);
>> -    if (pool->waiting) {
>> -        pool->waiting = false;
>> -        aio_co_wake(pool->main_co);
>> -    }
>> +    qemu_co_queue_restart_all(&pool->waiters);
>>   }
>>   void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool)
>>   {
>>       assert(pool->busy_tasks > 0);
>> -    assert(qemu_coroutine_self() == pool->main_co);
>> -    pool->waiting = true;
>> -    qemu_coroutine_yield();
>> +    qemu_co_queue_wait(&pool->waiters, NULL);
>> -    assert(!pool->waiting);
>>       assert(pool->busy_tasks < pool->max_busy_tasks);
> 
> As we wake up several coroutines now, I'm afraid this assertion may start to fire.
> And aio_task_pool_wait_one() becomes useless as a public API (still, it's used only locally, so we can make it static).
> 
> I'll send updated patch after reviewing the rest of the series.
> 

Hm, OK, we have two kinds of waiters: waiting for a slot and for all tasks to finish. So, either we need two queues, or do like this patch (one queue, but wake-up all waiters, for them to check does their condition satisfied or not).

I'm OK with this patch with the following squashed-in:

diff --git a/include/block/aio_task.h b/include/block/aio_task.h
index 50bc1e1817..50b1c036c5 100644
--- a/include/block/aio_task.h
+++ b/include/block/aio_task.h
@@ -48,7 +48,6 @@ bool aio_task_pool_empty(AioTaskPool *pool);
  void coroutine_fn aio_task_pool_start_task(AioTaskPool *pool, AioTask *task);
  
  void coroutine_fn aio_task_pool_wait_slot(AioTaskPool *pool);
-void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool);
  void coroutine_fn aio_task_pool_wait_all(AioTaskPool *pool);
  
  #endif /* BLOCK_AIO_TASK_H */
diff --git a/block/aio_task.c b/block/aio_task.c
index cf62e5c58b..7ba15ff41f 100644
--- a/block/aio_task.c
+++ b/block/aio_task.c
@@ -54,26 +54,17 @@ static void coroutine_fn aio_task_co(void *opaque)
      qemu_co_queue_restart_all(&pool->waiters);
  }
  
-void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool)
-{
-    assert(pool->busy_tasks > 0);
-
-    qemu_co_queue_wait(&pool->waiters, NULL);
-
-    assert(pool->busy_tasks < pool->max_busy_tasks);
-}
-
  void coroutine_fn aio_task_pool_wait_slot(AioTaskPool *pool)
  {
      while (pool->busy_tasks >= pool->max_busy_tasks) {
-        aio_task_pool_wait_one(pool);
+        qemu_co_queue_wait(&pool->waiters, NULL);
      }
  }
  
  void coroutine_fn aio_task_pool_wait_all(AioTaskPool *pool)
  {
      while (pool->busy_tasks > 0) {
-        aio_task_pool_wait_one(pool);
+        qemu_co_queue_wait(&pool->waiters, NULL);
      }
  }
Denis V. Lunev June 16, 2020, 2:49 p.m. UTC | #3
On 6/15/20 12:34 PM, Vladimir Sementsov-Ogievskiy wrote:
> 15.06.2020 10:47, Vladimir Sementsov-Ogievskiy wrote:
>> 11.06.2020 20:11, Denis V. Lunev wrote:
>>> From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>>
>>> Currently, aio task pool assumes that there is a main coroutine, which
>>> creates tasks and wait for them. Let's remove the restriction by using
>>> CoQueue. Code becomes clearer, interface more obvious.
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>>> CC: Kevin Wolf <kwolf@redhat.com>
>>> CC: Max Reitz <mreitz@redhat.com>
>>> CC: Stefan Hajnoczi <stefanha@redhat.com>
>>> CC: Fam Zheng <fam@euphon.net>
>>> CC: Juan Quintela <quintela@redhat.com>
>>> CC: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>>> CC: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>> CC: Denis Plotnikov <dplotnikov@virtuozzo.com>
>>> ---
>>>   block/aio_task.c | 21 ++++++---------------
>>>   1 file changed, 6 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/block/aio_task.c b/block/aio_task.c
>>> index 88989fa248..cf62e5c58b 100644
>>> --- a/block/aio_task.c
>>> +++ b/block/aio_task.c
>>> @@ -27,11 +27,10 @@
>>>   #include "block/aio_task.h"
>>>   struct AioTaskPool {
>>> -    Coroutine *main_co;
>>>       int status;
>>>       int max_busy_tasks;
>>>       int busy_tasks;
>>> -    bool waiting;
>>> +    CoQueue waiters;
>>>   };
>>>   static void coroutine_fn aio_task_co(void *opaque)
>>> @@ -52,31 +51,23 @@ static void coroutine_fn aio_task_co(void *opaque)
>>>       g_free(task);
>>> -    if (pool->waiting) {
>>> -        pool->waiting = false;
>>> -        aio_co_wake(pool->main_co);
>>> -    }
>>> +    qemu_co_queue_restart_all(&pool->waiters);
>>>   }
>>>   void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool)
>>>   {
>>>       assert(pool->busy_tasks > 0);
>>> -    assert(qemu_coroutine_self() == pool->main_co);
>>> -    pool->waiting = true;
>>> -    qemu_coroutine_yield();
>>> +    qemu_co_queue_wait(&pool->waiters, NULL);
>>> -    assert(!pool->waiting);
>>>       assert(pool->busy_tasks < pool->max_busy_tasks);
>>
>> As we wake up several coroutines now, I'm afraid this assertion may
>> start to fire.
>> And aio_task_pool_wait_one() becomes useless as a public API (still,
>> it's used only locally, so we can make it static).
>>
>> I'll send updated patch after reviewing the rest of the series.
>>
>
> Hm, OK, we have two kinds of waiters: waiting for a slot and for all
> tasks to finish. So, either we need two queues, or do like this patch
> (one queue, but wake-up all waiters, for them to check does their
> condition satisfied or not).
>
> I'm OK with this patch with the following squashed-in:
>
> diff --git a/include/block/aio_task.h b/include/block/aio_task.h
> index 50bc1e1817..50b1c036c5 100644
> --- a/include/block/aio_task.h
> +++ b/include/block/aio_task.h
> @@ -48,7 +48,6 @@ bool aio_task_pool_empty(AioTaskPool *pool);
>  void coroutine_fn aio_task_pool_start_task(AioTaskPool *pool, AioTask
> *task);
>  
>  void coroutine_fn aio_task_pool_wait_slot(AioTaskPool *pool);
> -void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool);
>  void coroutine_fn aio_task_pool_wait_all(AioTaskPool *pool);
>  
>  #endif /* BLOCK_AIO_TASK_H */
> diff --git a/block/aio_task.c b/block/aio_task.c
> index cf62e5c58b..7ba15ff41f 100644
> --- a/block/aio_task.c
> +++ b/block/aio_task.c
> @@ -54,26 +54,17 @@ static void coroutine_fn aio_task_co(void *opaque)
>      qemu_co_queue_restart_all(&pool->waiters);
>  }
>  
> -void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool)
> -{
> -    assert(pool->busy_tasks > 0);
> -
> -    qemu_co_queue_wait(&pool->waiters, NULL);
> -
> -    assert(pool->busy_tasks < pool->max_busy_tasks);
> -}
> -
>  void coroutine_fn aio_task_pool_wait_slot(AioTaskPool *pool)
>  {
>      while (pool->busy_tasks >= pool->max_busy_tasks) {
> -        aio_task_pool_wait_one(pool);
> +        qemu_co_queue_wait(&pool->waiters, NULL);
>      }
>  }
>  
>  void coroutine_fn aio_task_pool_wait_all(AioTaskPool *pool)
>  {
>      while (pool->busy_tasks > 0) {
> -        aio_task_pool_wait_one(pool);
> +        qemu_co_queue_wait(&pool->waiters, NULL);
>      }
>  }
>  
>
>
>
I'd better make this separate

Den

Patch
diff mbox series

diff --git a/block/aio_task.c b/block/aio_task.c
index 88989fa248..cf62e5c58b 100644
--- a/block/aio_task.c
+++ b/block/aio_task.c
@@ -27,11 +27,10 @@ 
 #include "block/aio_task.h"
 
 struct AioTaskPool {
-    Coroutine *main_co;
     int status;
     int max_busy_tasks;
     int busy_tasks;
-    bool waiting;
+    CoQueue waiters;
 };
 
 static void coroutine_fn aio_task_co(void *opaque)
@@ -52,31 +51,23 @@  static void coroutine_fn aio_task_co(void *opaque)
 
     g_free(task);
 
-    if (pool->waiting) {
-        pool->waiting = false;
-        aio_co_wake(pool->main_co);
-    }
+    qemu_co_queue_restart_all(&pool->waiters);
 }
 
 void coroutine_fn aio_task_pool_wait_one(AioTaskPool *pool)
 {
     assert(pool->busy_tasks > 0);
-    assert(qemu_coroutine_self() == pool->main_co);
 
-    pool->waiting = true;
-    qemu_coroutine_yield();
+    qemu_co_queue_wait(&pool->waiters, NULL);
 
-    assert(!pool->waiting);
     assert(pool->busy_tasks < pool->max_busy_tasks);
 }
 
 void coroutine_fn aio_task_pool_wait_slot(AioTaskPool *pool)
 {
-    if (pool->busy_tasks < pool->max_busy_tasks) {
-        return;
+    while (pool->busy_tasks >= pool->max_busy_tasks) {
+        aio_task_pool_wait_one(pool);
     }
-
-    aio_task_pool_wait_one(pool);
 }
 
 void coroutine_fn aio_task_pool_wait_all(AioTaskPool *pool)
@@ -98,8 +89,8 @@  AioTaskPool *coroutine_fn aio_task_pool_new(int max_busy_tasks)
 {
     AioTaskPool *pool = g_new0(AioTaskPool, 1);
 
-    pool->main_co = qemu_coroutine_self();
     pool->max_busy_tasks = max_busy_tasks;
+    qemu_co_queue_init(&pool->waiters);
 
     return pool;
 }