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SubjectRe: Memory upgrade: not faster / nfs
Date
In linux.dev.kernel, article <"sim0s4.fzi.178:25.10.96.16.26.14"@fzi.de>,
Christoph Trautwein <trautw@fzi.de> writes:
> ------- =_aaaaaaaaaa0
> Content-Type: text/plain; charset="us-ascii"
>
> Problem:
> ! NFS is a filesystem. Filesystems are not cached.
> ! The only thing that's cached in UN*X are block
> ! devices. This is the wrong place to cache.
>
This is true for UN*X in general, I'd say, but NOT for Linux 2.0.

-rwxr-xr-x 1 smurf user 412521 Feb 21 1996 XXX.eps

work:/uneu/urlichs 1243$ time cat XXX.eps >/dev/null
0.01user 0.22system 0:02.07elapsed 11%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+0minor)pagefaults 0swaps

work:/uneu/urlichs 1244$ time cat XXX.eps >/dev/null
0.02user 0.04system 0:00.08elapsed 75%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+0minor)pagefaults 0swaps

YOU tell me how to pull 5 MBytes/sec over a 10 MBit/sec Ethernet if you
don't believe me. :-)

> Is it correct how I see these things?
No.

> Why are filesystems not buffered?
Because initially, there were no file systems without a corresponding block
device, and buffering the whole device means fewer numbers to store. Plus,
the metadata on a file system obviously can't be cached in the file cache
because there's no file associated with them.

> Is there a nfs implementation that does buffering?
Yes. See above.

--
But we've only fondled the surface of that subject.
--Virginia Masters [of Master & Johnson]
--
Matthias Urlichs \ noris network GmbH / Xlink-POP Nürnberg
Schleiermacherstraße 12 \ Linux+Internet / EMail: urlichs@noris.de
90491 Nürnberg (Germany) \ Consulting+Programming+Networking+etc'ing
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Click <A HREF="http://info.noris.de/~smurf/finger">here</A>. 42

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