svn commit: r294471 - head/sys/dev/usb/wlan

[Andriy Gapon]

On 21/01/2016 03:28, Mark Johnston wrote:
> One feature that would be nice would be a way to associate KTR rings
> with arbitrary objects rather than having a single global ring (or
> per-CPU rings). For example, KTR_BUF lets one trace operations on
> filesystem buffers, but there's no good way to find all trace records
> corresponding to a given buf. At the moment one has to always include a
> pointer to the buf, and then scan *all* KTR entries for the pointer of
> interest while hoping that the relevant entries haven't already been
> overwritten. With per-object rings, one can in effect see a "history" of
> the object, whether it's a buf or a driver softc or whatever.
> 
> Isilon has done ad-hoc implementations of this for bufs and mbufs, and
> they're quite handy for debugging. With BUF_TRACKING enabled in our
> kernel config, each buf contains a const char *b_records[32], and one
> adds
> 
> 	buf_track(bp, __func__);
> 
> or so to various functions to record an entry in the buf when the
> function is invoked. This is really similar to what KTR does already,
> and I've needed to further hack up our buf tracking to include metadata
> (thread IDs) that KTR already provides. And, KTR records can be
> retrieved from vmcores by ktrdump -M.

Does your extension also save a stack trace?
I would love to have something like that for the memory allocation and
deallocation audit.

-- 
Andriy Gapon