Re: [PATCH v1 01/11] io_uring: support CQE32 in io_uring_cqe

[Stefan Roesch <shr@fb.com>]

On 4/21/22 6:51 PM, Kanchan Joshi wrote:
> On Thu, Apr 21, 2022 at 12:02 PM Stefan Roesch <shr@fb.com> wrote:
>>
>> This adds the struct io_uring_cqe_extra in the structure io_uring_cqe to
>> support large CQE's.
>>
>> Co-developed-by: Jens Axboe <axboe@kernel.dk>
>> Signed-off-by: Stefan Roesch <shr@fb.com>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>> ---
>>  include/uapi/linux/io_uring.h | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
>> index ee677dbd6a6d..6f9f9b6a9d15 100644
>> --- a/include/uapi/linux/io_uring.h
>> +++ b/include/uapi/linux/io_uring.h
>> @@ -111,6 +111,7 @@ enum {
>>  #define IORING_SETUP_R_DISABLED        (1U << 6)       /* start with ring disabled */
>>  #define IORING_SETUP_SUBMIT_ALL        (1U << 7)       /* continue submit on error */
>>  #define IORING_SETUP_SQE128    (1U << 8)       /* SQEs are 128b */
>> +#define IORING_SETUP_CQE32     (1U << 9)       /* CQEs are 32b */
>>
>>  enum {
>>         IORING_OP_NOP,
>> @@ -201,6 +202,11 @@ enum {
>>  #define IORING_POLL_UPDATE_EVENTS      (1U << 1)
>>  #define IORING_POLL_UPDATE_USER_DATA   (1U << 2)
>>
>> +struct io_uring_cqe_extra {
>> +       __u64   extra1;
>> +       __u64   extra2;
>> +};
>> +
>>  /*
>>   * IO completion data structure (Completion Queue Entry)
>>   */
>> @@ -208,6 +214,12 @@ struct io_uring_cqe {
>>         __u64   user_data;      /* sqe->data submission passed back */
>>         __s32   res;            /* result code for this event */
>>         __u32   flags;
>> +
>> +       /*
>> +        * If the ring is initialized with IORING_SETUP_CQE32, then this field
>> +        * contains 16-bytes of padding, doubling the size of the CQE.
>> +        */
>> +       struct io_uring_cqe_extra       b[0];
>>  };
> Will it be any better to replace struct b[0]  with "u64 extra[ ]" ?
> With that new fields will be referred as cqe->extra[0] and cqe->extra[1].
> 
> And if we go that route, maybe "aux" sounds better than "extra".

Let's use __u64 big_cqe[];