Re: [Patch] mm tracepoints

Larry Woodman
2009-03-06T12:35:18Z

On Fri, 2009-03-06 at 12:04 +0100, Ingo Molnar wrote:
> * 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

Yeah I'll fix that, it is a moving target.
>
> > > 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)

You mean in the filemap pagefault case???

Thanks, Larry

>
> Ingo