From: Blaisorblade <blaisorblade_spam@yahoo.it>
To: user-mode-linux-devel@lists.sourceforge.net
Cc: Nuno Silva <nuno.silva@vgertech.com>,
nils toedtmann <user-mode-linux-devel@nils.toedtmann.net>
Subject: Re: [uml-devel] Fighting latency
Date: Fri, 5 Nov 2004 20:38:15 +0100 [thread overview]
Message-ID: <200411052038.15491.blaisorblade_spam@yahoo.it> (raw)
In-Reply-To: <418AEB71.1090005@vgertech.com>
On Friday 05 November 2004 03:54, Nuno Silva wrote:
> Blaisorblade wrote:
>
> ...
>
> > A fix was proposed a while ago, which consisted in mlock()ing the memory.
> > But Jeff Dike refused it because he said "I want to write a much more
> > complex and more optimal solution. Mlock() is an hack".
Actually he said something much more complex than that. You can find his
worries in this email.
> Maybe having the linux binary in a ramfs will work better?
Wise idea! But you forgot the UML "RAM" from $TMPDIR.
Ramfs data are not swappable, so using that both for the UML binary and for *
$TMPDIR * should work.
However, Jeff wouldn't have a different opinion on this, but it can be done
without patching UML.
In fact, he worries about the host going OutOfMemory or anyway actually
needing hard to swap out memory; this could even happen when, for instance,
UML is using all memory just for caching (and maybe caching unused data). In
the meanwhile, while one UML caches an use-only-once file, the host goes
OutOfMemory and kills one UML instance. He wanted the UMLs to release memory
to the host when needed.
This, however, is not a problem for dedicated UML hosting if you don't
oversell UML ram.
> 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.
--
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729
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next prev parent reply other threads:[~2004-11-05 19:37 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 [this message]
2004-11-06 6:08 ` Nuno Silva
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