Messages in this thread | | | Date | Thu, 14 Jul 2022 21:57:48 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v4 1/1] perf/kprobe: maxactive for fd-based kprobe |
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On Thu, Jul 14, 2022 at 09:34:03PM +0200, Dmitrii Dolgov wrote: > From: Song Liu <songliubraving@fb.com> > > Enable specifying maxactive for fd based kretprobe. This will be useful > for tracing tools like bcc and bpftrace (see for example discussion [1]). > Use highest 4 bit (bit 59-63) to allow specifying maxactive by log2.
What's maxactive? This doesn't really tell me much. Why are the top 4 bits the best to use?
> > The original patch [2] seems to be fallen through the cracks and wasn't > applied. I've merely rebased the work done by Song Liu, verififed it > still works, and modified to allow specifying maxactive by log2 per > suggestion from the discussion thread.
That just doesn't belong in a Changelog.
> > Note that changes in rethook implementation may render maxactive > obsolete.
Then why bother creating an ABI for it?
> > [1]: https://github.com/iovisor/bpftrace/issues/835 > [2]: https://lore.kernel.org/all/20191007223111.1142454-1-songliubraving@fb.com/ > > Signed-off-by: Song Liu <songliubraving@fb.com> > Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com> > Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Lots of question and not a single answer in sight...
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