Re: [9fans] LinuxEMU

[David Leimbach <leimy2k@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 3549 bytes --]

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
>>
>>
>

[-- Attachment #2: Type: text/html, Size: 4470 bytes --]