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Re: [Qemu-devel] [PATCH 5/5] thread-pool: convert to use lock guards
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 5/5] thread-pool: convert to use lock guards |
Date: |
Fri, 8 Dec 2017 19:12:03 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 |
On 08/12/2017 16:13, Stefan Hajnoczi wrote:
>> - qemu_mutex_lock(&pool->lock);
>> + QEMU_LOCK_GUARD(QemuMutex, pool_guard, &pool->lock);
>> if (pool->idle_threads == 0 && pool->cur_threads < pool->max_threads) {
>> spawn_thread(pool);
>> }
>> QTAILQ_INSERT_TAIL(&pool->request_list, req, reqs);
>> - qemu_mutex_unlock(&pool->lock);
>> + qemu_lock_guard_unlock(&pool_guard);
> Why not QEMU_WITH_LOCK()? Then you can get rid of the explicit unlock.
I agree that QEMU_WITH_LOCK_GUARD is better in this case. (IIRC I wrote
this patch before coming up with the is_taken trick!).
My main question for the series is what you think the balance should be
between a more widely applicable API and a simpler one.
Thanks,
Paolo
>> @@ -330,7 +326,7 @@ void thread_pool_free(ThreadPool *pool)
>>
>> assert(QLIST_EMPTY(&pool->head));
>>
>> - qemu_mutex_lock(&pool->lock);
>> + QEMU_LOCK_GUARD(QemuMutex, pool_guard, &pool->lock);
>>
>> /* Stop new threads from spawning */
>> qemu_bh_delete(pool->new_thread_bh);
>> @@ -344,7 +340,7 @@ void thread_pool_free(ThreadPool *pool)
>> qemu_cond_wait(&pool->worker_stopped, &pool->lock);
>> }
>>
>> - qemu_mutex_unlock(&pool->lock);
>> + qemu_lock_guard_unlock(&pool_guard);
> Here too. I don't see the advantage of replacing a single lock/unlock
> with QEMU_LOCK_GUARD/unlock, if it cannot be made shorter/safer then
> it's fine to use QemuMutex directly.
- Re: [Qemu-devel] [PATCH 2/5] lock-guard: add scoped lock implementation, (continued)
[Qemu-devel] [PATCH 3/5] qemu-timer: convert to use lock guards, Paolo Bonzini, 2017/12/08
[Qemu-devel] [PATCH 4/5] qht: convert to use lock guards, Paolo Bonzini, 2017/12/08
[Qemu-devel] [PATCH 5/5] thread-pool: convert to use lock guards, Paolo Bonzini, 2017/12/08
Re: [Qemu-devel] [PATCH 5/5] thread-pool: convert to use lock guards, Eric Blake, 2017/12/08
Re: [Qemu-devel] [PATCH 5/5] thread-pool: convert to use lock guards, Peter Xu, 2017/12/11
Re: [Qemu-devel] [RFC PATCH 0/5] Scoped locks using attribute((cleanup)), Eric Blake, 2017/12/08