Re: [PATCHv2, RFC 12/30] thp, mm: add event counters for huge pagealloc on write to a file

[Ric Mason]

Hi Kirill,
On 03/26/2013 04:40 PM, Kirill A. Shutemov wrote:
> Dave Hansen wrote:
> > On 03/14/2013 10:50 AM, Kirill A. Shutemov wrote:
> > > --- a/include/linux/vm_event_item.h
> > > +++ b/include/linux/vm_event_item.h
> > > @@ -71,6 +71,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
> > >   		THP_FAULT_FALLBACK,
> > >   		THP_COLLAPSE_ALLOC,
> > >   		THP_COLLAPSE_ALLOC_FAILED,
> > > +		THP_WRITE_ALLOC,
> > > +		THP_WRITE_FAILED,
> > >   		THP_SPLIT,
> > >   		THP_ZERO_PAGE_ALLOC,
> > >   		THP_ZERO_PAGE_ALLOC_FAILED,
> > I think these names are a bit terse.  It's certainly not _writes_ that
> > are failing and "THP_WRITE_FAILED" makes it sound that way.
> Right. s/THP_WRITE_FAILED/THP_WRITE_ALLOC_FAILED/
>
> > Also, why do we need to differentiate these from the existing anon-hugepage
> > vm stats?  The alloc_pages() call seems to be doing the exact same thing in
> > the end.  Is one more likely to succeed than the other?
> Existing stats specify source of thp page: fault or collapse. When we
> allocate a new huge page with write(2) it's nither fault nor collapse. I
> think it's reasonable to introduce new type of event for that.

Why when we allocated a new huge page with write(2) is not a write fault?

>

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