linux-kernel - Re: [PATCH v9 06/12] mm: zero struct pages during initialization

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Date:   Wed, 4 Oct 2017 10:45:54 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Pasha Tatashin <pasha.tatashin@...cle.com>
Cc:     linux-kernel@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        x86@...nel.org, kasan-dev@...glegroups.com, borntraeger@...ibm.com,
        heiko.carstens@...ibm.com, davem@...emloft.net,
        willy@...radead.org, ard.biesheuvel@...aro.org,
        mark.rutland@....com, will.deacon@....com, catalin.marinas@....com,
        sam@...nborg.org, mgorman@...hsingularity.net,
        steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        bob.picco@...cle.com
Subject: Re: [PATCH v9 06/12] mm: zero struct pages during initialization

On Tue 03-10-17 11:22:35, Pasha Tatashin wrote:
> 
> 
> On 10/03/2017 09:08 AM, Michal Hocko wrote:
> > On Wed 20-09-17 16:17:08, Pavel Tatashin wrote:
> > > Add struct page zeroing as a part of initialization of other fields in
> > > __init_single_page().
> > > 
> > > This single thread performance collected on: Intel(R) Xeon(R) CPU E7-8895
> > > v3 @ 2.60GHz with 1T of memory (268400646 pages in 8 nodes):
> > > 
> > >                          BASE            FIX
> > > sparse_init     11.244671836s   0.007199623s
> > > zone_sizes_init  4.879775891s   8.355182299s
> > >                    --------------------------
> > > Total           16.124447727s   8.362381922s
> > 
> > Hmm, this is confusing. This assumes that sparse_init doesn't zero pages
> > anymore, right? So these number depend on the last patch in the series?
> 
> Correct, without the last patch sparse_init time won't change.

THen this is just misleading.
-- 
Michal Hocko
SUSE Labs