Re: [PATCH RFC 5.13 1/2] io_uring: add support for ns granularity of io_sq_thread_idle

[Hao Xu <haoxu@linux.alibaba.com>]

在 2021/4/28 下午10:16, Jens Axboe 写道:
> On 4/28/21 8:07 AM, Pavel Begunkov wrote:
>>> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
>>> index e1ae46683301..311532ff6ce3 100644
>>> --- a/include/uapi/linux/io_uring.h
>>> +++ b/include/uapi/linux/io_uring.h
>>> @@ -98,6 +98,7 @@ enum {
>>>   #define IORING_SETUP_CLAMP	(1U << 4)	/* clamp SQ/CQ ring sizes */
>>>   #define IORING_SETUP_ATTACH_WQ	(1U << 5)	/* attach to existing wq */
>>>   #define IORING_SETUP_R_DISABLED	(1U << 6)	/* start with ring disabled */
>>> +#define IORING_SETUP_IDLE_NS	(1U << 7)	/* unit of thread_idle is nano second */
>>>   
>>>   enum {
>>>   	IORING_OP_NOP,
>>> @@ -259,7 +260,7 @@ struct io_uring_params {
>>>   	__u32 cq_entries;
>>>   	__u32 flags;
>>>   	__u32 sq_thread_cpu;
>>> -	__u32 sq_thread_idle;
>>> +	__u64 sq_thread_idle;
>>
>> breaks userspace API
> 
> And I don't think we need to. If you're using IDLE_NS, then the value
> should by definition be small enough that it'd fit in 32-bits. If you
I make it u64 since I thought users may want a full flexibility to set
idle in nanosecond granularity(eg. (1e6 + 10) ns cannot be set by
millisecond granularity). But I'm not sure if this deserve changing the
userspace API.
> need higher timeouts, don't set it and it's in usec instead.
> 
> So I'd just leave this one alone.
>