Re: NFS root monitoring & system optimization

["Robb Main [Genedyne]" <genedyne@aci.on.ca>]

>
> You might be surprised.  If you're not swapping, busy shared libraries
> are not read from disk very often at all.  Opening a reference to an
> already open VM object does not require a disk transaction (save atime
> updates if enabled).
>

Dave,

Thanks for your comments.

My intention is to come up with some kind of "balance" between using RAM on
the diskless computer (i.e. embedded), and generating traffic on the
network.  Since I want to minimize traffic, I am not using the network block
device support to implement swapping over the network - there will be no
swapping. The obvious extreme case of this is just enough RAM to load the
kernel and application (plus a bit for shared stuff), and all other files
are dynamically loaded.

Now if you have tons of RAM (my test has 128MB - "Nobody needs more than
128MB" - and you can quote me on that... ;-), you might expect that a VM
object would either reside in RAM after loaded (i.e., not unloaded until
memory pages are required for something else...), or that it might reside in
the buffer cache on the DC after the initial open / load, but the log I saw
indicated otherwise - I saw several discrete loads logged by the NFS server
of the libc-2.1.2.so library.  On the server side, it appears that it does
maintain an open file handle for accessed files (ie. it doesn't close the
file after completing the access).  You can try this yourself (under
Slackware 7.0: "rpc.nfsd -d call", results in "/var/log/log.debug").

Your comment with respect to "atime" is valid, and I will be correcting this
("chattr +A"), and for that matter, I see no reason why many of the files
shouldn't be set immutable ("chattr +i").

Cheers,
Robb Main.


===========================================================================
This Mail was sent to netboot mailing list by:
"Robb Main [Genedyne]" <genedyne@aci.on.ca>
To get help about this list, send a mail with 'help' as the only string in
it's body to majordomo@baghira.han.de. If you have problems with this list,
send a mail to netboot-owner@baghira.han.de.