---------- Forwarded message ----------
From: Latchesar Ionkov <[EMAIL PROTECTED]>
Date: Dec 5, 2006 6:09 PM
Subject: Re: Re: Re: NFSv4/pNFS possible POSIX I/O API standards
To: Matthew Wilcox <[EMAIL PROTECTED]>
On 12/5/06, Matthew Wilcox <[EMAIL PROTECTED]> wrote:
On Tue, Dec 05, 2006 at 05:47:16PM +0100, Latchesar Ionkov wrote:
> I think that the main problem is that all these file systems resove a
> path name, one directory at a time bringing the server to its knees by
> the huge amount of requests. I would like to see what the performance
> is if you a) cache the last few hundred lookups on the server side,
> and b) modify VFS and the file systems to support multi-name lookups.
> Just assume for a moment that there is no any way to get these new
> operations in (which is probaly going to be true anyway :). What other
> solutions can you think of? :)
How exactly would you want a multi-name lookup to work? Are you saying
that open("/usr/share/misc/pci.ids") should ask the server "Find usr, if
you find it, find share, if you find it, find misc, if you find it, find
pci.ids"? That would be potentially very wasteful; consider mount
points, symlinks and other such effects on the namespace. You could ask
the server to do a lot of work which you then discard ... and that's not
efficient.
It could be wasteful, but it could (most likely) also be useful. Name
resolution is not that expensive on either side of the network. The
latency introduced by the single-name lookups is :)
Thanks,
Lucho
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