hpn_buffer_size

To: tech-net%netbsd.org@localhost
Subject: hpn_buffer_size
From: Petar Bogdanovic <petar%smokva.net@localhost>
Date: Fri, 27 Apr 2012 20:10:07 +0200
Hi,

I'm trying to figure out, why two nearly identical netbsd-6 hosts have
troubles using hpn.  They are connected through a 5000 Kb/s link and the
following (not very scientific) test:

        dd if=FILE bs=1m count=2 | ssh HOST dd bs=64k of=/dev/null

yields different results when defaults are in place (430KB/s) and when
HPNDisabled=yes and/or HPNBufferSize=2048 (590KB/s).

I did a diff on the -vvv output, but am not really sure how to interpret
the values:

        --- hpn.default   2012-04-27 19:42:26.000000000 +0200
        +++ hpn.disabled  2012-04-27 19:42:48.000000000 +0200
        @@ -126,329 +126,449 @@
         debug2: channel 0: open confirm rwindow 0 rmax 32768
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
        -debug2: channel 0: rcvd adjust 32768
        +debug2: channel 0: rcvd adjust 131072
         debug2: channel_input_status_confirm: type 99 id 0
         debug2: exec request accepted on channel 0
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
        -debug2: channel 0: rcvd adjust 32768
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
        -debug2: channel 0: rcvd adjust 32768
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
        -debug2: channel 0: rcvd adjust 32768
        (...same pattern for a while...)
        +debug2: channel 0: rcvd adjust 81920
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: channel 0: rcvd adjust 81920
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: channel 0: rcvd adjust 81920
        (...same pattern for a while...)
        @@ -489,6 +609,6 @@
         debug1: fd 0 clearing O_NONBLOCK
         debug1: fd 1 clearing O_NONBLOCK
         debug3: fd 2 is not O_NONBLOCK
        -Transferred: sent 2104512, received 4440 bytes, in 4.9 seconds
        -Bytes per second: sent 428033.4, received 903.0
        +Transferred: sent 2104512, received 3192 bytes, in 3.6 seconds
        +Bytes per second: sent 582904.2, received 884.1
         debug1: Exit status 0


        --- hpn.default 2012-04-27 19:42:26.000000000 +0200
        +++ hpn.2048    2012-04-27 19:43:14.000000000 +0200
        @@ -126,351 +126,645 @@
         debug2: channel 0: open confirm rwindow 0 rmax 32768
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
        -debug2: channel 0: rcvd adjust 32768
        +debug2: channel 0: rcvd adjust 2097152
         debug2: channel_input_status_confirm: type 99 id 0
         debug2: exec request accepted on channel 0
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
        -debug2: channel 0: rcvd adjust 32768
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
         debug2: tcpwinsz: 33580 for connection: 5
        (..............)
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: channel 0: rcvd adjust 131072
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: tcpwinsz: 33580 for connection: 5
        +debug2: channel 0: rcvd adjust 131072
        (..............)
        @@ -489,6 +783,6 @@
         debug1: fd 0 clearing O_NONBLOCK
         debug1: fd 1 clearing O_NONBLOCK
         debug3: fd 2 is not O_NONBLOCK
        -Transferred: sent 2104512, received 4440 bytes, in 4.9 seconds
        -Bytes per second: sent 428033.4, received 903.0
        +Transferred: sent 2102624, received 2904 bytes, in 3.7 seconds
        +Bytes per second: sent 573858.1, received 792.6
         debug1: Exit status 0


I'm fine with disabling HPN but something tells me that hpn is supposed
to work out of the box and it took me quite a while to understand that
it wasn't $some_application 's fault so lets help those googlers..

Thanks,

                Petar Bogdanovic
Follow-Ups:
- Re: hpn_buffer_size
  - From: Thor Lancelot Simon
- Re: hpn_buffer_size
  - From: Chuck Swiger
- Re: hpn_buffer_size
  - From: Thor Lancelot Simon
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