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From: Pavel Begunkov <[email protected]>
To: Hao Xu <[email protected]>, Jens Axboe <[email protected]>
Cc: [email protected], Joseph Qi <[email protected]>
Subject: Re: [PATCH RFC 5.13 1/2] io_uring: add support for ns granularity of io_sq_thread_idle
Date: Thu, 29 Apr 2021 10:11:55 +0100	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 4/29/21 4:41 AM, Hao Xu wrote:
> 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

It's a really weird user requiring such a precision. u32 allows up to
~1s, and if more is needed users can switch to ms mode, so in the worst
case the precision is 1/1000 of the desired value, more than enough.

> millisecond granularity). But I'm not sure if this deserve changing the
> userspace API.
 
That's not about deserve or not, we can't break ABI. Can be worked around,
e.g. by taking resv fields, but don't see a reason

>> need higher timeouts, don't set it and it's in usec instead.
>>
>> So I'd just leave this one alone.
>>
> 

-- 
Pavel Begunkov

  reply	other threads:[~2021-04-29  9:12 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-28 13:32 [PATCH RFC 5.13 0/2] adaptive sqpoll and its wakeup optimization Hao Xu
2021-04-28 13:32 ` [PATCH RFC 5.13 1/2] io_uring: add support for ns granularity of io_sq_thread_idle Hao Xu
2021-04-28 14:07   ` Pavel Begunkov
2021-04-28 14:16     ` Jens Axboe
2021-04-28 14:53       ` Pavel Begunkov
2021-04-28 14:54         ` Jens Axboe
2021-04-29  3:41       ` Hao Xu
2021-04-29  9:11         ` Pavel Begunkov [this message]
2021-05-05 14:07           ` Hao Xu
2021-05-05 17:40             ` Pavel Begunkov
2021-04-29  3:28     ` Hao Xu
2021-04-29 22:15       ` Pavel Begunkov
2021-09-26 10:00         ` Hao Xu
2021-09-28 10:51           ` Pavel Begunkov
2021-09-29  7:52             ` Hao Xu
2021-09-29  9:24             ` Hao Xu
2021-09-29 11:37               ` Pavel Begunkov
2021-09-29 12:13                 ` Hao Xu
2021-09-30  8:51                   ` Pavel Begunkov
2021-09-30 12:04                     ` Pavel Begunkov
2021-10-05 15:00                       ` Hao Xu
2021-04-28 13:32 ` [PATCH RFC 5.13 2/2] io_uring: submit sqes in the original context when waking up sqthread Hao Xu
2021-04-28 14:12   ` Jens Axboe
2021-04-29  4:12     ` Hao Xu
2021-04-28 14:34   ` Pavel Begunkov
2021-04-28 14:37     ` Pavel Begunkov
2021-04-29  4:37       ` Hao Xu
2021-04-29  9:28         ` Pavel Begunkov
2021-05-05 11:20           ` Hao Xu
2021-04-28 14:39     ` Jens Axboe
2021-04-28 14:50       ` Pavel Begunkov
2021-04-28 14:53         ` Jens Axboe
2021-04-28 14:56           ` Pavel Begunkov
2021-04-28 15:09             ` Jens Axboe
2021-04-29  4:43       ` Hao Xu
2021-04-29  8:44     ` Hao Xu
2021-04-29 22:10       ` Pavel Begunkov
2021-05-05 13:10         ` Hao Xu
2021-05-05 17:44           ` Pavel Begunkov
2021-04-29 22:02   ` Pavel Begunkov

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