Re: io_submit() taking a long time to return ?

[Zach Brown]

> By reading the aio documentation, we expected the io_submit call to
> always return immediately,

Sadly, that isn't guaranteed.

> but in our preliminary tests we noticed that
> sometimes this call can take a long time (more than 10 ms, even
> sometimes more than 30 ms !!).

If I had to guess I'd suspect that these delays are due to sync block
mapping lookups in the submit path.  Do these tend to show up the first
time you read a file?

- z
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