linux-kernel - Re: [RFC] [PATCH 8/9] memcg: remove page

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: <200809120000.37901.nickpiggin@yahoo.com.au>
Date:	Fri, 12 Sep 2008 00:00:37 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	balbir@...ux.vnet.ibm.com, "xemul@...nvz.org" <xemul@...nvz.org>,
	"hugh@...itas.com" <hugh@...itas.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, menage@...gle.com
Subject: Re: [RFC] [PATCH 8/9] memcg: remove page_cgroup pointer from memmap

On Thursday 11 September 2008 21:22, KAMEZAWA Hiroyuki wrote:
> Remove page_cgroup pointer from struct page.
>
> This patch removes page_cgroup pointer from struct page and make it be able
> to get from pfn. Then, relationship of them is
>
> Before this:
>   pfn <-> struct page <-> struct page_cgroup.
> After this:
>   struct page <-> pfn -> struct page_cgroup -> struct page.

So...

pfn -> *hash* -> struct page_cgroup, right?

While I don't think there is anything wrong with the approach, I
don't understand exactly where you guys are hoping to end up with
this?

I thought everyone was happy with preallocated page_cgroups because
of their good performance and simplicity, but this seems to be
going the other way again.

I'd worry that the hash and lookaside buffers and everything makes
performance more fragile, adds code and data and icache to fastpaths.
--
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/