On 11/15/23 2:36 AM, Jens Axboe wrote:
> if (has_lock && (ctx->flags & IORING_SETUP_SQPOLL)) {
> struct io_sq_data *sq = ctx->sq_data;
>
>- if (mutex_trylock(&sq->lock)) {
>- if (sq->thread) {
>- sq_pid = task_pid_nr(sq->thread);
>- sq_cpu = task_cpu(sq->thread);
>- }
>- mutex_unlock(&sq->lock);
>- }
>+ sq_pid = sq->task_pid;
>+ sq_cpu = sq->sq_cpu;
> }
There are two problems:
1.The output of SqThread is inaccurate. What is actually recorded is the PID of the parent process.
2. Sometimes it can output, sometimes it outputs -1.
The test results are as follows:
Every 0.5s: cat /proc/9572/fdinfo/6 | grep Sq
SqMask: 0x3
SqHead: 6765744
SqTail: 6765744
CachedSqHead: 6765744
SqThread: -1
SqThreadCpu: -1
SqBusy: 0%
-------------------------------------------
Every 0.5s: cat /proc/9572/fdinfo/6 | grep Sq
SqMask: 0x3
SqHead: 7348727
SqTail: 7348728
CachedSqHead: 7348728
SqThread: 9571
SqThreadCpu: 174
SqBusy: 95%
