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Re: systemtap/pcp integration
- From: fche at redhat dot com (Frank Ch. Eigler)
- To: David Smith <dsmith at redhat dot com>
- Cc: Systemtap List <systemtap at sourceware dot org>, pcp <pcp at oss dot sgi dot com>
- Date: Fri, 18 Jul 2014 11:49:01 -0400
- Subject: Re: systemtap/pcp integration
- Authentication-results: sourceware.org; auth=none
- References: <53C83CB9 dot 3020808 at redhat dot com>
Hi, David -
> Here's a small update on the prototype systemtap/pcp integration work
> I'm doing.
Thanks, what a great start.
> I've create a systemtap branch, called 'dsmith/mmv' that contains
> all my work. Basically this work allows systemtap to create 'mmv'
> memory mapped files.
(That's git://sourceware.org/git/systemtap.git branch dsmith/mmv.)
> [...] The code works for the attached script, but I'm sure it is
> quite fragile. Things like locking, error checking, documentation,
> etc. need to be done. [...]
Overall, are you happy with the general approach of reusing the exact
MMV format (and thus the PMDA)?
At one point I suggested reworking the earlier prototype so that the
bulk of the MMV format's emulation would be based on tapset script
code (and possibly more declarative / dynamic / safe) rather than C.
Have you come to any conclusions about the propriety of that?
How much post-initialization change can the MMV format tolerate, as
regarding indom contents or metric availability? I assume such
metadata changes are synchronized with the PMDA via the generation
numbers. Moving around contents of the mmap region as in
__stp_mmv_alloc_data_item sounds like it leaves the data inconsistent
during the process; does it need similar protection?
- FChE