About the status of hugepage filtering!

Baoquan He bhe at redhat.com
Mon Apr 28 05:46:35 PDT 2014

On 04/28/14 at 12:21pm, Petr Tesarik wrote:
> On Mon, 28 Apr 2014 15:56:05 +0800
> Baoquan He <bhe at redhat.com> wrote:
> > Hi Astushi,
> > 
> > I remember earlier Jingbai posted a patchset on hugepage filtering,
> > later you pasted your hugepage filtering prototype patch, and people
> > thought yours is better. So now may I know the status and what's your
> > plan?
> > 
> > Because in makedumpfile 1.5.6, this is not delivered. Your plan can help
> > us much.
> Hi Baoquan,
> I followed up on Atsushi's prototype, and there's a patch series
> sitting on my disk which just came too late for 1.5.6, so I held it
> back. It was also suggested that the mdf_pfn cleanup patch be applied
> first. That one is now in, and I'll send an updated series shortly.
> The first part of the change is the "Generic handling of multi-page
> exclusions", that is a method which can be used for excluding both free
> pages and compound pages (and without adding even more complexity to
> the calculation of the cycle size).
> The second part is handling of hugepages. This simply extends the
> algorithm so that all pages in a compound page are treated as one
> object. To make it work, additional info must be exported from the
> kernel. This is where I got stuck with my previous attempt. For now,
> this patch is already in the mm tree:
> http://ozlabs.org/~akpm/mmotm/broken-out/kexec-save-pg_head_mask-in-vmcoreinfo.patch

Hi Petr,

Good to know this progress. And it's awesome that kernel patch exporting
PG_head_mask has been in mm tree.

I saw people had discussed heatedly about the generic handling of
multi-page exclusions. So as long as the first part passes through and
merged in, hugepage filtering adding will be supported very smoothly, is
that right? I didn't follow up that thread very closely, if yes, it's a
great news. And thanks for your effort.


> Petr T

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