linux-kernel - Re: [PATCH 1/3] mm, numa: rework do_pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180105180905.GR2801@dhcp22.suse.cz>
Date:   Fri, 5 Jan 2018 19:09:05 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Christopher Lameter <cl@...ux.com>
Cc:     Anshuman Khandual <khandual@...ux.vnet.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Zi Yan <zi.yan@...rutgers.edu>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Vlastimil Babka <vbabka@...e.cz>,
        Andrea Reale <ar@...ux.vnet.ibm.com>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] mm, numa: rework do_pages_move

On Fri 05-01-18 11:15:18, Cristopher Lameter wrote:
> On Fri, 5 Jan 2018, Michal Hocko wrote:
> 
> > Yes. I am really wondering because there souldn't anything specific to
> > improve the situation with patch 2 and 3. Likewise the only overhead
> > from the patch 1 I can see is the reduced batching of the mmap_sem. But
> > then I am wondering what would compensate that later...
> 
> Could you reduce the frequency of taking mmap_sem? Maybe take it when
> picking a new node and drop it when done with that node before migrating
> the list of pages?

I believe there should be some cap on the number of pages. We shouldn't
keep it held for million of pages if all of them are moved to the same
node. I would really like to postpone that to later unless it causes
some noticeable regressions because this would complicate the code
further and I am not sure this is all worth it.

-- 
Michal Hocko
SUSE Labs