Hi Brendan, On Sun, Jul 19, 2015 at 10:47:31PM -0700, Brendan Gregg wrote: > G'Day Masami-san, Namhyung, > > I'm really looking forward to this feature -- very useful, thanks!... > > On Sat, Jul 18, 2015 at 9:24 PM, Namhyung Kim <namhy...@kernel.org> wrote: > > Hi Masami, > > > > On Fri, Jul 17, 2015 at 12:21:42PM +0900, Masami Hiramatsu wrote: > >> Now I'm thinking that we should avoid using %event syntax for perf-list > >> and perf-record to avoid confusion. For example, suppose that we have > >> "libfoo:bar" SDT event, when we just scanned the libfoo binary and > >> use it via perf-record, we'll run perf record -e "%libfoo:bar". > >> However, after we set the probe via perf-probe, we have to run > >> perf record -e "libfoo:bar". That difference looks no good. > >> So, I think in both case it should accept -e "libfoo:bar" syntax. > > > > I don't remember how the SDT events should be shown to users. Sorry > > if I'm missing something here. > > > > AFAIK an SDT event consists of a provider and an event name. So it > > can be simply 'provider:event' like tracepoints or > > 'binary:provider_event' like uprobes. > > > > I like the former because it's simpler but it needs to guarantee that > > it doesn't clash with existing tracepoints/[ku]probes. So IIUC we > > chose the '%' sign to distinguish them. But after setting a probe at > > it, the group name should be the binary name. So the whole event name > > might be changed, and this is not good. > > I don't think we should worry about the clash, as the provider name > should differentiate.
But there's no guarantee. Maybe an userspace tool which deals with a kernel module has SDT names as same as the kernel module's tracepoint names. It might or might not be a problem if we can handle those duplicate names somehow. > So I think "libfoo:bar" with perf record is > better. After adding them to the cache (via % if needed), I'd think > they would be best looking like tracepoints. Eg, listing them together > they can be differentiated, something like: > > # perf list > [...] > block:block_rq_abort [Tracepoint event] > block:block_rq_requeue [Tracepoint event] > block:block_rq_complete [Tracepoint event] > [...] > libc:memory_heap_new [User tracepoint event] > libc:memory_heap_free [User tracepoint event] > libc:memory_heap_more [User tracepoint event] > [...] > > Then used the same. Yes, as I said I also prefer this simpler form. Maybe we can choose to use another names for low-level plumbing inside the perf tools, but I still think that users should be able to use simple names like above. Thanks, Namhyung -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
