[dpdk-dev] [PATCH 2/2] lib/librte_eal: Remove unnecessary hugepage zero-filling

[Wang, Zhihong]

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com]
> Sent: Wednesday, November 25, 2015 7:04 AM
> To: Stephen Hemminger <stephen at networkplumber.org>
> Cc: Wang, Zhihong <zhihong.wang at intel.com>; dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 2/2] lib/librte_eal: Remove unnecessary
> hugepage zero-filling
> 
> 2015-11-24 14:44, Stephen Hemminger:
> > On Tue, 24 Nov 2015 22:13:28 +0100
> > Thomas Monjalon <thomas.monjalon at 6wind.com> wrote:
> >
> > > 2015-11-22 18:28, Stephen Hemminger:
> > > > On Sun, 22 Nov 2015 14:13:35 -0500 Zhihong Wang
> > > > <zhihong.wang at intel.com> wrote:
> > > >
> > > > > The kernel fills new allocated (huge) pages with zeros.
> > > > > DPDK just has to populate page tables to trigger the allocation.
> > > > >
> > > > > Signed-off-by: Zhihong Wang <zhihong.wang at intel.com>
> > > >
> > > > Nice, especially on slow machines or with large memory.
> > > >
> > > > Acked-by: Stephen Hemminger <stephen at networkplumber.org>
> > >
> > > Yes very nice.
> > > I think it's too late to integrate this change which can have some
> > > unpredictable side effects.
> > > Do you agree to wait for 2.3?
> >
> > What side effects? Either it is zero or it is not.
> > Only some broken architecture would have an issue.
> 
> I mean it changes the memory allocator behaviour. It's not something we want to
> discover a new bug just before the release.
> This kind of important change must be integrated at the beginning of the release
> cycle.
> I'm asking for opinions because it would be really nice to have.

Literally this patch doesn't change anything, it just keeps DPDK from zero-filling pages again which have just been zero-filled.
It would be nice to have this patch in DPDK 2.2 since it can reduce the startup time nearly by half for hugepage cases.
But I understand longer merge/test window make it safer for a release.
It makes sense either way.