[CRIU] p.haul page statistics

[Mike Rapoport]

On Wed, Sep 14, 2016 at 03:53:49PM +0300, Mike Rapoport wrote:
> On Wed, Sep 14, 2016 at 12:05:49PM +0300, Pavel Emelyanov wrote:
> > On 09/13/2016 08:18 PM, Adrian Reber wrote:
> > > On Tue, Sep 13, 2016 at 06:12:28PM +0300, Pavel Emelyanov wrote:
> > >> On 09/12/2016 03:08 PM, Mike Rapoport wrote:
> > >>> On Mon, Sep 12, 2016 at 11:02:34AM +0200, Adrian Reber wrote:
> > >>>> On Thu, Sep 08, 2016 at 08:39:06AM +0300, Mike Rapoport wrote:
> > >>
> > >> Erm... I saw Adrian's thoughts on counting lazy pages as written, but now I
> > >> disagree with that. If we treat pages_written as "pages that went into the
> > >> image file", then this definition is clean and understandable. But how to
> > >> define pages_written if we count lazy pages there as well?
> > >>
> > >> Can we better leave pages_written as "pages that are in the images" and, if
> > >> we need it, introduce pages_dumped to count all the pages that are to be
> > >> taken with us regardless whether they are in the image or lazy?
> > > 
> > > The problem I see is with p.haul during the pre-dump. Maybe pages should
> > > not be counted as lazy in the pre-dump case. There is no use to count
> > > lazy pages during pre-dump.
> > 
> > Agreed. On pre-dump lazy pages do not make sense. But AFAIU they are not
> > counted.
> 
> The short answer is "the lazy pages are always counted as lazy".
> 
> The longer story is that at the point when the pages are collected to pipes
> and counted, the "lazy" has notion means "the page belongs to VMA that
> userfaultfd can handle". Therefore, the ppb's marked as PPB_LAY may or may
> not get written to the images, depending on the options.
> 
> We can add sixth parameter to generate_iovs, so that it'll be able to tell
> whether it should count lazy pages or not. But, IMHO, it'll make memory
> dump path even "nicer" than it is now.
> 
> In the current state, which is certainly buggy, PAGES_WRITTEN counts only
> pages that cannot be handled by userfaultfd, and PAGES_LAZY counts pages
> that can be handled by userfaultfd.
> 
> The patch above in this thread makes sure that PAGES_WRITTEN counts all the
> pages that are in the images, while keeping PAGES_LAZY intact.

So, how do we want to move forward with fixing the stats reporting?
 
> > 
> > > 		Adrian
> > > .
> 
> --
> Sincerely yours,
> Mike.
> 
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