[9fans] Re: Kfs file server

[9fans] Re: Kfs file server

[G.David]

From: Kenji Arisawa <arisawa@aichi-u.ac.jp>

>Kfs file server of plan9 looks too slow.

[snip]

>Coping on 9fs involves bi-directional transmission
>through 10 base ethernet using 9P protocol.
>The value is reasonable and may be efficient.
>If we apply 100 base ethernet, this time will largely improved.

What are you using as a file server?  A plan9 fileserver works
very well.

>However why the result of kfs is so bad?
>Caching problem?

This is the main reason.  The kfs system does no caching of the
hard drive.  There have been other discussions of this topic and
the best idea forwarded so far is to integrate the mount driver
with the memory system to use "unused" memory for a cache.  This
would improve both kfs and 9p.  Using the QID of the file to flush
old contents keeps the cache in sync with the fileserver.  This
implies that each block transfered from the cache should wait for
a walk from the fileserver to verify the QID.  Doing it just on
the open is not good enough.  Of course, the cache has to be
write-through.

>Algorithm?

It is the same one in the fileserver.  It is simple and fast.

>Can I improve this value?

Easily.

David Butler
gdb@dbSystems.com

[9fans] Re: Kfs file server

[forsyth]

disk/kfs does cache the hard disc, but if you've got heaps
of physical memory (and why not) it might not be using
as much of it as you'd like.   i think it caps the cache at 2Mbytes.

the 4.3bsd figure is possibly misleading since it's quite likely to be reflecting
the time taken to copy from one part of memory to another,
with nothing much done with the disc.  i'd try a file that's much
bigger than physical memory.