From: Christoph Lameter <clameter@sgi.com>
To: Andi Kleen <ak@suse.de>
Cc: linux-kernel@vger.kernel.org, Martin Bligh <mbligh@google.com>,
Christoph Hellwig <hch@infradead.org>,
Marcelo Tosatti <marcelo@kvack.org>,
Arjan van de Ven <arjan@infradead.org>,
Nick Piggin <nickpiggin@yahoo.com.au>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [RFC 5/8] x86_64 without ZONE_DMA
Date: Fri, 7 Jul 2006 18:25:22 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.64.0607071820570.4530@schroedinger.engr.sgi.com> (raw)
In-Reply-To: <200607080300.16931.ak@suse.de>
On Sat, 8 Jul 2006, Andi Kleen wrote:
> > The savings are not only from the code paths. The VM itself is cleaner and
> > the balancing issues are not that troublesome anymore.
>
> Doesn't help - it has to be fixed anyways for NUMA and other architectures.
Some architectures like ours can run with a single zone since they have
DMA that works anywhere. Same thing is true for my machines are home and
at work.
> Also in my experience empty zones are not a significant problem for VM
> balancing.
The problem is that the zones are not even empty! We keep 16M in some
weird ZONE_DMA that barely anyone one uses anymore and add slabs to it
that are only used by some confused device drivers.
Also the empty zones are still a problem since they have to be scanned
repeatedly (potentially on each allocation). They waste cachelines and
result in loops where we could just have straight code.
next prev parent reply other threads:[~2006-07-08 1:25 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-08 0:05 [RFC 0/8] Optional ZONE_DMA Christoph Lameter
2006-07-08 0:05 ` [RFC 1/8] Add CONFIG_ZONE_DMA to all archesM Christoph Lameter
2006-07-10 0:52 ` KAMEZAWA Hiroyuki
2006-07-10 15:56 ` Christoph Lameter
2006-07-11 7:11 ` KAMEZAWA Hiroyuki
2006-07-08 0:05 ` [RFC 2/8] slab allocator: Make DMA support configurable Christoph Lameter
2006-07-08 0:05 ` [RFC 3/8] eventcounters: Optional ZONE_DMA Christoph Lameter
2006-07-08 0:05 ` [RFC 4/8] page allocator: " Christoph Lameter
2006-07-08 0:23 ` Andi Kleen
2006-07-08 0:41 ` Christoph Lameter
2006-07-08 0:05 ` [RFC 5/8] x86_64 without ZONE_DMA Christoph Lameter
2006-07-08 0:20 ` Andi Kleen
2006-07-08 0:42 ` Christoph Lameter
2006-07-08 1:00 ` Andi Kleen
2006-07-08 1:25 ` Christoph Lameter [this message]
2006-07-08 0:05 ` [RFC 6/8] i386 " Christoph Lameter
2006-07-08 0:05 ` [RFC 7/8] Single zone optimizations Christoph Lameter
2006-07-08 0:19 ` Andi Kleen
2006-07-08 0:05 ` [RFC 8/8] Optimize mempolicies for a single zone Christoph Lameter
2006-07-08 0:17 ` Andi Kleen
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