linux-kernel - Re: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP

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Message-ID: <20171016173358.t3twty3wttbutcro@dhcp22.suse.cz>
Date:   Mon, 16 Oct 2017 19:33:58 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Christopher Lameter <cl@...ux.com>
Cc:     Pavel Machek <pavel@....cz>,
        Mike Kravetz <mike.kravetz@...cle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Michal Nazarewicz <mina86@...a86.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Guy Shattah <sguy@...lanox.com>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>,
        Laura Abbott <labbott@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP_CONTIG) support

On Mon 16-10-17 11:02:24, Cristopher Lameter wrote:
> On Mon, 16 Oct 2017, Michal Hocko wrote:
> 
> > > So I mmap(MAP_CONTIG) 1GB working of working memory, prefer some data
> > > structures there, maybe recieve from network, then decide to write
> > > some and not write some other.
> >
> > Why would you want this?
> 
> Because we are receiving a 1GB block of data and then wan to write it to
> disk. Maybe we want to modify things a bit and may not write all that we
> received.
 
And why do you need that in a single contiguous numbers? If performance,
do you have any numbers that would clearly tell the difference?

-- 
Michal Hocko
SUSE Labs