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#40 Slirp still slow

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nobody
None
2
2007-01-15
2007-01-15
Robert de Bath
No

The performance of the slirp interface has improved however it's still very slow compared to the TAP interface.

On my machine:
TAP32: localhost <-> colinux approx 6..10MBytes/s

This is reasonable but not really anywhere near the disk limit, processor usage is high but there appears to be some headroom.

SLIRP: To Colinux 3MByte/s, this is OK but isn't limited by anything obvious, neither the CPU nor the disk are maxed out.

Slirp, from CoLinux 500Kbyte/s
This is so bad that I had to add a TAP interface for X. Everything looks idle; the 100Mbyte file tested was cached in RAM.

Discussion

  • Robert de Bath
    Robert de Bath
    2007-01-15

    • priority: 5 --> 2
     
  • Henry N.
    Henry N.
    2007-01-15

    • milestone: 647238 -->
     
  • Henry N.
    Henry N.
    2007-01-15

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    Incrase the task priority of colinux-slirp-net-daemon, this is one of the todo for next releases.

     
  • Henry N.
    Henry N.
    2007-01-19

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    http://www.henrynestler.com/colinux/autobuild/devel-20070117/
    Last autobuild has slirp improvements, from updating qemu sources.
    The most interesting is the incrasing MSS from 512 to 1460, this reduce the packet reassabling overhead. Slirp should go faster now.

    Would you test the slirp speed under your same environment and please report the results?

     
  • Robert de Bath
    Robert de Bath
    2007-02-03

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    Tried the 2007-01-17 build.

    The transfer into CoLinux using slirp is now running at about 6MBytes per second.
    The transfer from CoLinux to a remote are still running at approx 500kbyte/s. NASTY.

    The Slirp measurements were made to a remote (100BaseT) server. Before as well as this time. The 6MBytes/s is maxing out the remote server (it's an old machine).
    So I've relocated to a better server, one with a gigabit network card like the portable...

    First I tested the server with another linux machine. On 100baseT it ran at 11MBytes/s on a 1000BaseT it ran at 29MBytes/s upload to the server 25MBytes/s from the server to a little 1Ghz box, this appears to be disk limited.

    I'm still getting the same speeds from CoLinux. Maybe 6.1MBytes/s download.
    Getting suspicious I try the same FTP using a windows FTP client (LeechFTP) and sure enough the download from the server is at about 6MBytes/s. OTOH the upload is about 12MBytes/s not as good as a machine a third the power of the portable but a little different to the CoLinux upload speed.

    I also tried the bridge device 10MB/s download (1 Hyperthread-CPU pegged) 5MB/s upload (1 HtCPU at 80%)

    I'm gonna see if I can improve my windows download speed now ... unlikely though.

     
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    Despite the improvement wishes I can give you an advice:

    You should always use as tap interface for X. I use one in the 172.16.0.x network only for X.

    eth1=tuntap,TAP-LOOP

    where TAP-LOOP is a TAP Win32 adpater using 172.16.0.3 and eth1 uses 172.16.0.2. (I use 2 separate TAP Win32 adapters, 2nd is for LAN (eth0) and slirp covers WLAN (eth2).

    This resulted in best performance for X and works even if there is no other network.

    Bebbo