Re: [PATCH] io_uring: don't iterate ctx list to update sq_thread_idle

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

在 2021/3/15 下午6:49, Pavel Begunkov 写道:
> On 15/03/2021 08:56, Hao Xu wrote:
>> sqd->sq_thread_idle can be updated by a simple max(), rather than
>> iterating the whole ctx list to get the max one.
> 
> I left it as a more fool proof option. Do you have a performance issue
> with it? E.g. dozens rings sharing a single SQPOLL and constantly adding
> new ones.
Currently no performance cases, just happen to see this and make
the code change.
> 
>>
>> Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
>> ---
>>   fs/io_uring.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index a4bce17af506..17697b9890e3 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -7871,7 +7871,7 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx,
>>   			ret = -ENXIO;
>>   		} else {
>>   			list_add(&ctx->sqd_list, &sqd->ctx_list);
>> -			io_sqd_update_thread_idle(sqd);
>> +			sqd->sq_thread_idle = max(sqd->sq_thread_idle, ctx->sq_thread_idle);
>>   		}
>>   		io_sq_thread_unpark(sqd);
>>   
>>
>