On 9/7/20 10:14 AM, Jens Axboe wrote:
> On 9/7/20 2:56 AM, Xiaoguang Wang wrote:
>> 3. When it's appropriate to set ctx's IORING_SQ_NEED_WAKEUP flag? In
>> your current implementation, if a ctx is marked as SQT_IDLE, this ctx
>> will be set IORING_SQ_NEED_WAKEUP flag, but if other ctxes have work
>> to do, then io_sq_thread is still running and does not need to be
>> waken up, then a later wakeup form userspace is unnecessary. I think
>> it maybe appropriate to set IORING_SQ_NEED_WAKEUP when all ctxes have
>> no work to do, you can have a look at my attached codes:)
>
> That's a good point, any chance I can get you to submit a patch to fix
> that up?
Something like this?
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 4bd18e01ae89..80913973337a 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6747,8 +6747,6 @@ static enum sq_ret __io_sq_thread(struct io_ring_ctx *ctx,
goto again;
}
- io_ring_set_wakeup_flag(ctx);
-
to_submit = io_sqring_entries(ctx);
if (!to_submit || ret == -EBUSY)
return SQT_IDLE;
@@ -6825,6 +6823,8 @@ static int io_sq_thread(void *data)
io_run_task_work();
cond_resched();
} else if (ret == SQT_IDLE) {
+ list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
+ io_ring_set_wakeup_flag(ctx);
schedule();
start_jiffies = jiffies;
}
--
Jens Axboe
