Re: [Lsf-pc] [LSF/MM TOPIC] really large storage sectors - goingbeyond 4096 bytes
From: Joel Becker
Date: Thu Jan 23 2014 - 16:21:48 EST
On Thu, Jan 23, 2014 at 07:55:50AM -0500, Theodore Ts'o wrote:
> On Thu, Jan 23, 2014 at 07:35:58PM +1100, Dave Chinner wrote:
> > >
> > > I expect it would be relatively simple to get large blocksizes working
> > > on powerpc with 64k PAGE_SIZE. So before diving in and doing huge
> > > amounts of work, perhaps someone can do a proof-of-concept on powerpc
> > > (or ia64) with 64k blocksize.
> > Reality check: 64k block sizes on 64k page Linux machines has been
> > used in production on XFS for at least 10 years. It's exactly the
> > same case as 4k block size on 4k page size - one page, one buffer
> > head, one filesystem block.
> This is true for ext4 as well. Block size == page size support is
> pretty easy; the hard part is when block size > page size, due to
> assumptions in the VM layer that requires that FS system needs to do a
> lot of extra work to fudge around. So the real problem comes with
> trying to support 64k block sizes on a 4k page architecture, and can
> we do it in a way where every single file system doesn't have to do
> their own specific hacks to work around assumptions made in the VM
Yup, ditto for ocfs2.
"One of the symptoms of an approaching nervous breakdown is the
belief that one's work is terribly important."
- Bertrand Russell
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