Messages in this thread | | | Date | Tue, 4 Aug 2009 22:35:26 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 4/4] tracing, page-allocator: Add a postprocessing script for page-allocator-related ftrace events |
| |
* Andrew Morton <akpm@linux-foundation.org> wrote:
> On Tue, 4 Aug 2009 21:57:17 +0200 > Ingo Molnar <mingo@elte.hu> wrote: > > > Let me demonstrate these features in action (i've applied the > > patches for testing to -tip): > > So? The fact that certain things can be done doesn't mean that > there's a demand for them, nor that anyone will _use_ this stuff.
c'mon Andrew ...
Did you never want to see whether firefox is leaking [any sort of] memory, and if yes, on what callsites? Try something like on an already running firefox context:
perf stat -e kmem:mm_page_alloc \ -e kmem:mm_pagevec_free \ -e kmem:mm_page_free_direct \ -p $(pidof firefox-bin) sleep 10
... and "perf record" for the specific callsites.
this perf stuff is immensely flexible and a very unixish abstraction. The perf.data contains timestamped trace entries of page allocations and freeing done.
[...] > It would be nice to at least partially remove the vmstat/meminfo > infrastructure but I don't think we can do that?
at least meminfo is an ABI for sure - vmstat too really.
But we can stop adding new fields into obsolete, inflexible and clearly deficient interfaces, and we can standardize new instrumentation to use modern instrumentation facilities - i.e. tracepoints and perfcounters.
I'm not saying to put a tracepoint on every second line of the kernel, but obviously Mel and Rik wanted this kind of info because they found it useful in practice.
Ingo
| |