linux-kernel - Re: [ 20/27] s390/mm: have 16 byte aligned struct 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: <20121207100007.GB5129@osiris.de.ibm.com>
Date:	Fri, 7 Dec 2012 11:00:07 +0100
From:	Heiko Carstens <heiko.carstens@...ibm.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	alan@...rguk.ukuu.org.uk,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	CAI Qian <caiqian@...hat.com>
Subject: Re: [ 20/27] s390/mm: have 16 byte aligned struct pages

On Thu, Dec 06, 2012 at 04:59:04PM -0800, Greg Kroah-Hartman wrote:
> 3.6-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Heiko Carstens <heiko.carstens@...ibm.com>
> 
> commit 4bffbb3455372a26816e364fb4448810f7014452 upstream.
> 
> Select HAVE_ALIGNED_STRUCT_PAGE on s390, so that the slub allocator can make
> use of compare and swap double for lockless updates. This increases the size
> of struct page to 64 bytes (instead of 56 bytes), however the performance gain
> justifies the increased size:
> 
> - now excactly four struct pages fit into a single cache line; the
>   case that accessing a struct page causes two cache line loads
>   does not exist anymore.
> - calculating the offset of a struct page within the memmap array
>   is only a simple shift instead of a more expensive multiplication.
> 
> A "hackbench 200 process 200" run on a 32 cpu system did show an 8% runtime
> improvement.
> 
> Signed-off-by: Heiko Carstens <heiko.carstens@...ibm.com>
> Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
> Signed-off-by: CAI Qian <caiqian@...hat.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

Same as for 3.4: compare and swap double is not available for 3.6 on s390.

--
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/