Re: [Patch] mm tracepoints

[Ingo Molnar <mingo@elte.hu>]

* Steven Rostedt <rostedt@goodmis.org> wrote:

> 
> On Fri, 6 Mar 2009, KOSAKI Motohiro wrote:
> 
> > > I've implemented several mm tracepoints to track page allocation and
> > > freeing, various types of pagefaults and unmaps, and critical page
> > > reclamation routines.  This is useful for debugging memory allocation
> > > issues and system performance problems under heavy memory loads:
> > > 
> > > # tracer: mm
> > > #
> > > #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
> > > #              | |       |          |         |
> > >          pdflush-624   [004]   184.293169: wb_kupdate:
> > > (mm_pdflush_kupdate) count=3e48
> > >          pdflush-624   [004]   184.293439: get_page_from_freelist:
> > > (mm_page_allocation) pfn=447c27 zone_free=1940910
> > >         events/6-33    [006]   184.962879: free_hot_cold_page:
> > > (mm_page_free) pfn=44bba9
> > >       irqbalance-8313  [001]   188.042951: unmap_vmas:
> > > (mm_anon_userfree) mm=ffff88044a7300c0 address=7f9a2eb70000 pfn=24c29a
> > >              cat-9122  [005]   191.141173: filemap_fault:
> > > (mm_filemap_fault) primary fault: mm=ffff88024c9d8f40 address=3cea2dd000
> > > pfn=44d68e
> > >              cat-9122  [001]   191.143036: handle_mm_fault:
> > > (mm_anon_fault) mm=ffff88024c8beb40 address=7fffbde99f94 pfn=24ce22
> > > ...
> > 
> > Hi Larry,
> > 
> > I've started to evaluate your patch.
> > 
> > firstly, this patch can't apply tip/master.

yeah, would be nice to have a patch against:

  http://people.redhat.com/mingo/tip.git/README

> > secondly, I don't think the address of mm_struct and pfn 
> > help to analysis. administrator don't know the page is which 
> > file's cache.
> 
> The mm_struct may not be helpful since there should be a 1 to 
> 1 mapping between user tasks and the mm struct. Hmm, maybe 
> not, due to threads?

Correct - so the mm ID looks useful.

> But the pfn is helpful since it is a unique identifier for 
> what physical page was mapped.

Yeah. Nevertheless some sort of filename:offset indicator would 
be nice too. (as an add-on)

	Ingo