public inbox for [email protected]
 help / color / mirror / Atom feed
* Question about patch "io_uring: add submission polling"
@ 2020-10-16  8:55 Xiaoguang Wang
  2020-10-16 13:27 ` Jens Axboe
  0 siblings, 1 reply; 3+ messages in thread
From: Xiaoguang Wang @ 2020-10-16  8:55 UTC (permalink / raw)
  To: io-uring; +Cc: [email protected], Pavel Begunkov, Stefano Garzarella

hi,

I have questions about below code comments, which was included in patch
"io_uring: add submission polling",
------------------------------------------------------------
     /*
      * Drop cur_mm before scheduling, we can't hold it for
      * long periods (or over schedule()). Do this before
      * adding ourselves to the waitqueue, as the unuse/drop
      * may sleep.
      */
     if (cur_mm) {
             unuse_mm(cur_mm);
             mmput(cur_mm);
             cur_mm = NULL;
     }

     prepare_to_wait(&ctx->sqo_wait, &wait, TASK_INTERRUPTIBLE);
-------------------------------------------------------------
Stefano submited a patch "io_uring: prevent sq_thread from spinning when it should stop",
I understand what issue Stefano fixed, but don't understand below comments.

Can anyone help to explain why we need to rop cur_mm before scheduling, or
why we can't hold it for long periods (or over schedule()), and if we
unuse/drop mm after adding ourselves to the waitqueue, what issue will
happen when unuse/drop sleeps, thanks.

Regards,
Xiaoguang Wang

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2020-10-19  2:53 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-10-16  8:55 Question about patch "io_uring: add submission polling" Xiaoguang Wang
2020-10-16 13:27 ` Jens Axboe
2020-10-19  2:52   ` Xiaoguang Wang

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox