linux-kernel - Re: [RFC 0/4] Transparent on-demand struct page initialization embedded in the buddy allocator

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: <51E628F8.6030303@gmail.com>
Date:	Wed, 17 Jul 2013 13:17:44 +0800
From:	Sam Ben <sam.bennn@...il.com>
To:	Robin Holt <holt@....com>
CC:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	Nate Zimmer <nzimmer@....com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux MM <linux-mm@...ck.org>, Rob Landley <rob@...dley.net>,
	Mike Travis <travis@....com>,
	Daniel J Blueman <daniel@...ascale-asia.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	Yinghai Lu <yinghai@...nel.org>, Mel Gorman <mgorman@...e.de>
Subject: Re: [RFC 0/4] Transparent on-demand struct page initialization embedded
 in the buddy allocator

On 07/12/2013 10:03 AM, Robin Holt wrote:
> We have been working on this since we returned from shutdown and have
> something to discuss now.  We restricted ourselves to 2MiB initialization
> to keep the patch set a little smaller and more clear.
>
> First, I think I want to propose getting rid of the page flag.  If I knew
> of a concrete way to determine that the page has not been initialized,
> this patch series would look different.  If there is no definitive
> way to determine that the struct page has been initialized aside from
> checking the entire page struct is zero, then I think I would suggest
> we change the page flag to indicate the page has been initialized.
>
> The heart of the problem as I see it comes from expand().  We nearly
> always see a first reference to a struct page which is in the middle
> of the 2MiB region.  Due to that access, the unlikely() check that was
> originally proposed really ends up referencing a different page entirely.
> We actually did not introduce an unlikely and refactor the patches to
> make that unlikely inside a static inline function.  Also, given the
> strong warning at the head of expand(), we did not feel experienced
> enough to refactor it to make things always reference the 2MiB page
> first.
>
> With this patch, we did boot a 16TiB machine.  Without the patches,
> the v3.10 kernel with the same configuration took 407 seconds for
> free_all_bootmem.  With the patches and operating on 2MiB pages instead
> of 1GiB, it took 26 seconds so performance was improved.  I have no feel
> for how the 1GiB chunk size will perform.

How to test how much time spend on free_all_bootmem?

>
> I am on vacation for the next three days so I am sorry in advance for
> my infrequent or non-existant responses.
>
>
> Signed-off-by: Robin Holt <holt@....com>
> Signed-off-by: Nate Zimmer <nzimmer@....com>
> To: "H. Peter Anvin" <hpa@...or.com>
> To: Ingo Molnar <mingo@...nel.org>
> Cc: Linux Kernel <linux-kernel@...r.kernel.org>
> Cc: Linux MM <linux-mm@...ck.org>
> Cc: Rob Landley <rob@...dley.net>
> Cc: Mike Travis <travis@....com>
> Cc: Daniel J Blueman <daniel@...ascale-asia.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Greg KH <gregkh@...uxfoundation.org>
> Cc: Yinghai Lu <yinghai@...nel.org>
> Cc: Mel Gorman <mgorman@...e.de>
> --
> 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/

--
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/