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Date:   Tue, 3 Jul 2018 09:28:35 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Jia He <hejianet@gmail.com>
Cc:     Russell King <linux@armlinux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mel Gorman <mgorman@suse.de>,
        Will Deacon <will.deacon@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Pavel Tatashin <pasha.tatashin@oracle.com>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        AKASHI Takahiro <takahiro.akashi@linaro.org>,
        Gioh Kim <gi-oh.kim@profitbricks.com>,
        Steven Sistare <steven.sistare@oracle.com>,
        Daniel Vacek <neelx@redhat.com>,
        Eugeniu Rosca <erosca@de.adit-jv.com>,
        Vlastimil Babka <vbabka@suse.cz>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, James Morse <james.morse@arm.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Steve Capper <steve.capper@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        Philippe Ombredanne <pombredanne@nexb.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Kemi Wang <kemi.wang@intel.com>,
        Petr Tesarik <ptesarik@suse.com>,
        YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Nikolay Borisov <nborisov@suse.com>, richard.weiyang@gmail.com
Subject: Re: [PATCH v9 0/6] optimize memblock_next_valid_pfn and
 early_pfn_valid on arm and arm64
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On Tue 03-07-18 10:11:11, Jia He wrote:
> On 7/2/2018 7:40 PM, Michal Hocko Wrote:
[...]
> > So this is 13ms saving when booting 96G machine. Is this really worth
> > the additional code? Are there any other benefits?
> Sorry, Michal
> I missed one thing.
> This 13ms optimization is merely the result of my patch 3~6
> Patch 1 is originated by Paul Burton in commit b92df1de5d289.
> In its description,
> ===
> James said "I have tested this patch on a virtual model of a Samurai CPU
>     with a sparse memory map.  The kernel boot time drops from 109 to
>     62 seconds. "
> ===

Those numbers should be in the changelog.
-- 
Michal Hocko
SUSE Labs