linux-kernel - Re: [PATCH] mm: introduce numa_zero

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, 12 Dec 2012 21:15:29 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Joonsoo Kim <js1304@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	andi@...stfloor.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH] mm: introduce numa_zero_pfn

> I would expect a processor to fetch the zero page cachelines from the l3
> cache from other sockets avoiding memory transactions altogether. The zero
> page is likely in use somewhere so no typically no memory accesses should
> occur in a system.

It depends on how effectively the workload uses the caches. If something
is a cache pig of the L3 cache, then even shareable cache lines may need
to be refetched regularly.

But if your workloads spends a significant part of its time reading
from zero page read only data there is something wrong with the workload.

I would do some data profiling first to really prove that is the case.

-Andi
--
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/