From: Nuno Silva <nuno.silva@vgertech.com>
To: Blaisorblade <blaisorblade_spam@yahoo.it>
Cc: user-mode-linux-devel@lists.sourceforge.net,
nils toedtmann <user-mode-linux-devel@nils.toedtmann.net>
Subject: Re: [uml-devel] Fighting latency
Date: Sat, 06 Nov 2004 06:08:50 +0000 [thread overview]
Message-ID: <418C6A72.4080807@vgertech.com> (raw)
In-Reply-To: <200411052038.15491.blaisorblade_spam@yahoo.it>
Blaisorblade wrote:
>>Maybe having the linux binary in a ramfs will work better?
>
> Wise idea! But you forgot the UML "RAM" from $TMPDIR.
No i didn't :-) And i advise against it because of the problems that you
point out below (OOM). Anyway, if the data is frequently used it won't
be sent to swap... If you only touch that data once every 5 minutes and
you have some memory pressure you may get a bigger latency.
If you must have fast-as-it-gets memory access making several UBDs, one
of them very small in ramfs, may be better, YMMV.
...
>>You can also do some creative mount --bind, to mount only one ramfs
>>instance, if you have many UMLs running.
>
> Not needed I think - use different names for UML binaries as needed. It will
> pickup a good name for the RAM file.
I was thinking about chroot environments. And saving some MB by using
the same binary - living in ramfs - to run many UMLs.
Regarding double-cacheing you may try NFS or directIO (with directIO the
guest can create disk I/O even if it's not needed and ruin the host's
I/O performance). Again, YMMV.
Thanks,
Nuno Silva
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prev parent reply other threads:[~2004-11-06 6:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-04 15:50 [uml-devel] Fighting latency nils toedtmann
2004-11-04 23:44 ` Blaisorblade
2004-11-05 2:54 ` Nuno Silva
2004-11-05 19:38 ` Blaisorblade
2004-11-06 6:08 ` Nuno Silva [this message]
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