Re: [Qemu-devel] Re: Network Performance between Win Host and Linux

[Leonardo E. Reiter]

On an additional note, Windows host users may want to try moving the 
arbitrary Sleep() in main_loop_wait() to the end of the function, and 
making that conditional if there are no I/O events pending.  Otherwise, 
there is a fixed penalty and this does not take advantage of Ken's new 
patch to avoid the delay if there are pending slirp requests for 
example.  When I have some time I will see if there is a better way to 
multiplex poll in Windows, so that you can use something like select() 
but still get interrupted.  There might for example be something 
relevant in the newer winsock libraries (i.e. V2), but of course it has 
to be general enough to work on any type of fd.

I apologize but I have not yet been able to successfully build QEMU on 
Windows, even after mucking with the mingw stuff.  I probably need to 
spend more time on it at some point.  But if anyone is using Windows and 
can compile QEMU from source, you can try moving the Sleep to see if 
that helps, especially after applying Ken's new patches.  Actually 
Kazu's patch for TAP performance addresses this for TAP for example, so 
it should be easy to adapt to slirp... the code is in very close proximity.

- Leo Reiter

Kenneth Duda wrote:
> The "qemu-slirp-performance" patch contains three improvements to qemu
> slirp networking performance.  Booting my virtual machine (which
> NFS-mounts its root filesystem from the host) has been accelerated by
> 8x, from over 5 minutes to 40 seconds.  TCP throughput has been
> accelerated from about 2 megabytes/sec to 9 megabytes/sec, in both
> directions (measured using a simple python script).  The system is
> subjectively more responsive (for activities such as logging in or
> running simple python scripts).

--
Leonardo E. Reiter
Vice President of Product Development, CTO

Win4Lin, Inc.
Virtual Computing from Desktop to Data Center
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