Re: [PATCH v1 0/1] Add an option to stop blktrace based on events recorded

[Jeff Moyer <jmoyer@redhat.com>]

Stephen Bates <sbates@raithlin.com> writes:

> Hi Jeff
>
>> Can you expand on the use case?  Why is the number of events a useful
>> parameter?
>>
>> Thanks,
>> Jeff
>
> I am working on tying blktrace into a prometheus exporter so I can
> monitor block-level activity across a fleet of storage servers. I
> don't want to overload either the storage server CPUs or the exporter
> itself when the server is under high load so I want to avoid using the
> time-based argument for blktrace.
>
> If I have access to an events based option I can run this knowing that
> in high-load situations I will not be capturing many, many IO and
> perhaps slowing down the server in the process.
>
> Does that make sense?

Yes, thanks for the clarification.  Originally I thought you might be
using the number of events as a proxy for the size of data collected.
I'm still not sure how a user would reason about how many events is too
many (or enough), but that's a not a problem for blktrace to figure out.

I'll reply to the patch with my comments.

Cheers,
Jeff