From: Dave Chinner <david@fromorbit.com>
To: Stan Hoeppner <stan@hardwarefreak.com>
Cc: xfs@oss.sgi.com
Subject: Re: block sizes > 4K ?? possible w/large page support?
Date: Tue, 12 Jun 2012 09:56:12 +1000 [thread overview]
Message-ID: <20120611235612.GF22848@dastard> (raw)
In-Reply-To: <4FD606C1.1070103@hardwarefreak.com>
On Mon, Jun 11, 2012 at 09:54:57AM -0500, Stan Hoeppner wrote:
> On 6/11/2012 8:29 AM, Carlos Maiolino wrote:
>
> > The maximum block size of a XFS filesystem is 64kiB. But in linux it's limited
> > to the PAGE_SIZE value.
>
> Correct.
>
> > so, on x86 architectures, the maximum block size is
> > 4kiB.
>
> Not entirely correct. Since ~1996, 16 years ago, PPro and higher 32bit
> CPUs with PSE/PSE36 support pages of 4MB, or 2MB with PAE enabled.
>
> x86-64 CPUs in long mode also support a 2MB page size. But the problem
> of internal fragmentation may outweigh the TLB and other benefits of
> these very large pages. I'm not an MM dev so I can't elaborate further.
> There may be other issues.
>
> > although it could benefit from a 16kiB page size, you'll need to be running an
> > operating system which supports this page size value.
>
> And AFAIK the kernel MM team doesn't have x86 2MB pages on their radar.
> Or do they?
Been supported for a few of years now in one form or another.
google for "transparent huge pages".....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2012-06-11 23:56 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-11 3:21 block sizes > 4K ?? possible w/large page support? Linda A. Walsh
2012-06-11 13:13 ` Stan Hoeppner
2012-06-11 13:29 ` Carlos Maiolino
2012-06-11 14:54 ` Stan Hoeppner
2012-06-11 16:21 ` Carlos Maiolino
2012-06-11 21:25 ` Stefan Ring
2012-06-11 23:56 ` Dave Chinner [this message]
2012-06-12 0:08 ` Dave Chinner
2012-06-12 2:32 ` Eric Sandeen
2012-06-12 17:37 ` Linda A. Walsh
2012-06-12 18:55 ` Eric Sandeen
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