linux-kernel - Re: [RFC 00/15] x86_64: Optimize percpu accesses

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: <48764619.9040708@goop.org>
Date:	Thu, 10 Jul 2008 10:25:45 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Christoph Lameter <cl@...ux-foundation.org>
CC:	Mike Travis <travis@....com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Arjan van de Ven <arjan@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jack Steiner <steiner@....com>, linux-kernel@...r.kernel.org,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [RFC 00/15] x86_64: Optimize percpu accesses

Christoph Lameter wrote:
> Jeremy Fitzhardinge wrote:
>
>   
>> You want to virtually map the percpu area?  How and when would it get
>> extended?
>>     
>
> It would get extended when cpu_alloc() is called and the allocator finds that there is no per cpu memory available.
>   

Which, I take it, allocates percpu memory.  It would have the same 
caveats as vmalloc memory, with respect to accessing it during fault 
handlers and nmi handlers, I take it.

How would cpu_alloc() actually get used?  It doesn't make much sense for 
general code, since we don't have the notion of a percpu pointer to 
memory (vs a pointer to percpu memory).  Is the intended use for 
allocating percpu memory in modules?  What other uses?

    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/