linux-kernel - Re: [PATCH 2/9] ksm: let shared pages be swappable

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]

Date:	Fri, 4 Dec 2009 14:16:17 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	Andrea Arcangeli <aarcange@...hat.com>,
	Rik van Riel <riel@...hat.com>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Izik Eidus <ieidus@...hat.com>,
	Chris Wright <chrisw@...hat.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 2/9] ksm: let shared pages be swappable

On Fri,  4 Dec 2009 14:06:07 +0900 (JST)
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> wrote:

> > Umm?? Personally I don't like knob. If you have problematic workload,
> > please tell it us. I will try to make reproduce environment on my box.
> > If current code doesn't works on KVM or something-else, I really want
> > to fix it.
> > 
> > I think Larry's trylock idea and your 64 young bit idea can be combinate.
> > I only oppose the page move to inactive list without clear young bit. IOW,
> > if VM pressure is very low and the page have lots young bit, the page should
> > go back active list although trylock(ptelock) isn't contended.
> > 
> > But unfortunatelly I don't have problem workload as you mentioned. Anyway
> > we need evaluate way to your idea. We obviouslly more info.
> 
> [Off topic start]
> 
> Windows kernel have zero page thread and it clear the pages in free list
> periodically. because many windows subsystem prerefer zero filled page.
> hen, if we use windows guest, zero filled page have plenty mapcount rather
> than other typical sharing pages, I guess.
> 
> So, can we mark as unevictable to zero filled ksm page? 
> 

Hmm, can't we use ZERO_PAGE we have now ?
If do so,
 - no mapcount check
 - never on LRU
 - don't have to maintain shared information because ZERO_PAGE itself has
   copy-on-write nature.

Thanks,
-Kame

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/