Re: [9fans] LinuxEMU

[Eric Van Hensbergen <ericvh@gmail.com>]

http://www.linux-kvm.org/wiki/images/4/41/KvmForum2008$kdf2008_16.pdf

On Mon, Jan 18, 2010 at 3:20 PM, David Leimbach <leimy2k@gmail.com> wrote:
> Also, the more I think about it, the more interesting I think it is to run
> different OSes in different domains on the same machines anyway.  If you
> want to make one thing work with another, we've got cool stuff like 9p and
> v9fs to bridge gaps.
> This is a very good way to force a separation of concerns between layers
> anyway.  L4 seems to have a way for linux processes to talk to other L4
> processes using L4 IPC when it's used for virtualization, so why not use 9P
> to talk across virtualization domains?
> Dave
>
> On Mon, Jan 18, 2010 at 3:16 PM, David Leimbach <leimy2k@gmail.com> wrote:
>>
>> Good post!  Thanks for the information.  I have looked at linux traces
>> before and couldn't figure out why the hell so much crap was being done.
>>  It's as if glibc is throwing calls at the system to figure out which kernel
>> it's on - another good argument for the FreeBSD model of keeping kernel and
>> userspace in sync with one another.
>> (typed on my fucking macbook)
>> Dave
>>
>> On Mon, Jan 18, 2010 at 2:43 PM, <cinap_lenrek@gmx.de> wrote:
>>>
>>> i think a lot of the slowdown comes from that linux was not
>>> streamlined its userspace, but the userspace just got more and more
>>> complicated and does tons of redundant stuff...  what they did then
>>> was not to fix userspace, but they optimized the kernel to cache
>>> anything...
>>>
>>> look at some typical syscall traces...  tons of files are stat()ed...
>>> multiple times...  it opens unix domain sockets to talk to a not
>>> existant ldap name service or something...  tons of shared libraries
>>> are loaded...  and that is all before even your main() entry is gets
>>> called...
>>>
>>> linuxemu doesnt shortcut these things...  i cant reuse the shared
>>> library mmaps on exec ect...  i think walks are not cached in plan9,
>>> so you have to talk to your fileserver.
>>>
>>> the syscall overhead is just one of the bottlenecks of linux emulation
>>> and you would have to put tons of more crap in the kernel to get
>>> mozilla or opera working...  and even more to get it half as fast as
>>> in linux.
>>>
>>> just keep plan9 small and simple.  you dont want to maintain something
>>> as complex and optimized-to-death as the full linux kernel with all
>>> that caching and read aheading and 100 different stat syscalls.
>>>
>>> we shouldnt be araid of writing new programs and dont concentrate on
>>> keeping the legacy alive so mutch.  you can even run linux/major os
>>> side by side with plan9 these days on virtual machines.  and this gets
>>> cheaper every day without doing anything.  in fact this seems to be
>>> what most people on iwp9 where doing.  (on ther fucking macbooks)
>>>
>>> ;-)
>>>
>>> --
>>> cinap
>>>
>>>
>>> ---------- Forwarded message ----------
>>> From: David Leimbach <leimy2k@gmail.com>
>>> To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
>>> Date: Mon, 18 Jan 2010 11:15:43 -0800
>>> Subject: [9fans] LinuxEMU
>>> The SVN thread got me thinking that I had remembered seeing Ron post
>>> something about what I thought was an in-kernel LinuxEMU that got a little
>>> better performance on plan 9.
>>> Is this true?  I know the currently LinuxEMU is pretty impressive and can
>>> run a large range of programs (Web browsers even!), but that sometimes the
>>> performance is a little bit less than what might be desired.   I believe
>>> this was due to extra system call overheads for each linux kernel call.
>>> Does anyone know what I'm talking about or am I just babbling away here?
>>> Dave
>>
>
>