linux-kernel - Re: [patch 05/14] percpu: Use a Kconfig variable to configure arch specific percpu setup

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:	Wed, 28 Nov 2007 17:42:24 -0800
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Christoph Lameter <clameter@....com>
CC:	Rusty Russell <rusty@...tcorp.com.au>, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, Andi Kleen <ak@...e.de>
Subject: Re: [patch 05/14] percpu: Use a Kconfig variable to configure arch
 specific percpu setup

Christoph Lameter wrote:
> On Wed, 28 Nov 2007, Jeremy Fitzhardinge wrote:
>
>   
>> I don't see the problem.  The way i386 does it inherently supports
>> per-cpu data very early on (it uses the prototype percpu section until
>> the real percpu values are set up).
>>     
>
> Ok so we could do that for x86_64 as well? There is more complicated 
> bootstrap since i386 does not support NUMA aware placement of per cpu 
> areas.
>   

Don't think it matters either way.  Before percpu is allocated, NUMA
issues don't matter.  Once they are - by whatever mechanism - you can
set the segment bases up appropriately.  The fact that you chose to put
percpu data at address X doesn't affect the percpu mechanism one way or
the other.

> percpu references are quite frequent already (vm statistics) and will be 
> more frequent after we have converted the per cpu arrays to per cpu 
> allocations.
>   

Well, I think the point is moot, because x86 will always use 32-bit
offsets.  Each reference will only be 1 byte bigger than a normal
variable reference.

    J
-
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/