Messages in this thread | | | Subject | Re: [Patch] mm tracepoints | From | Larry Woodman <> | Date | Fri, 06 Mar 2009 14:06:14 -0500 |
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On Fri, 2009-03-06 at 18:38 +0100, Peter Zijlstra wrote: > On Fri, 2009-03-06 at 18:10 +0100, Ingo Molnar wrote: > > Looks pretty good and useful to me. I've Cc:-ed more mm folks, > > it would be nice to hear their opinion about these tracepoints. > > > > Andrew, Nick, Peter, what do you think? > > Bit sad we use the struct mm_struct * as mm identifier (little %lx vs %p > confusion there too), but I suppose there simply isn't anything better. > > Exposing kernel pointers like that might upset some of the security > folks, not sure if I care though. > > I'm missing the fault_filemap_read counterpart of fault_anon_pgin.
filemap_fault handles both the initial fault when the pte is zero and pagein when the page has been reclaimed. It was impossible to implement them as separate handlers in __do_fault() without changing the underlying MM code.
> > Once you have anon/filemap symmetric, you might consider folding these > and doing the anon argument thing you do elsewhere. > > Initially I was thinking we lacked the kswapd vs direct reclaim > information on the pgout data, but since we log the pid:comm for each > event...
They are separate, trace_mm_kswapd_runs() and trace_mm_directreclaim_reclaimall(). trace_mm_directreclaim_reclaimzone() is for the zone_reclaim path where we do local zone reclamation rather than falling off to the next zone in the zone list.
> > Which brings us to mm_pdflush_*, we can already see its pdflush from > pid:comm, then again, it fits the naming style. Same for > mm_directreclaim*() - we already know its direct, since its not kswapd > doing it. >
Like I said above there are 2 direct reclaim paths: one is teh call to try_to_free_pages() out of __alloc_pages_internal() and the other is the call to shrink_zone() out of __zone_reclaim(). I made a distinction between these because the first calls shrink_zone for each zone in the zone list when memory is really low(below min) where the second calls shrink_zone for the local zone to prevent memory allocation from a remote node.
> Finally, we have page_free, but not page_alloc? Oh, it is there, just > not in the obvious place.
In order to get the zone free information it has to be in down in get_page_from_freelist.
> > > Things missing, we trace unmap, but not mmap, mprotect, mlock? > I was concentrating more on the operations that traced a page moving throughout the system. mmap and mprotect operate on the virtual address space instead of the pages mapped in that address space.
Larry
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