[Vortex] Tuning window size in vortex to achieve more performance

Francis Brosnan Blazquez francis at aspl.es
Wed Sep 5 16:02:33 CEST 2012

> Hi

Hi Subrahmanya,

> In vortex channel window size is hard-coded to 4096. It is the same in
> Java implementation of BEEP that we are using. While testing the
> performance of Java BEEP implementation we observed that changing the
> following gives very good performance improvement.
> 1. Increasing the window size to a larger value (4 * 4096) 

Just to confirm increasing the window size to 32k (as you do) provides
important performance improvements...going over only consumes memory
without providing significant performance improvements..

> 2. Changing the condition to identify when to send sequence frames.
> After the change the peer would not wait for half of the window to
> become free to send SEQ frame instead it would send once the free
> window size reaches a particular limit which will be lesser than 2048
> (around 500 or so).

We've tested this and we always get better performance following RFC
indications about considering half of the available window as a good
limit to issue a SEQ frame...

> Now I want to make similar changes in vortex and test it. For that I
> looked at vortex source to find out the places where to make these
> changes. Below are the identified places. Can someone confirm whether
> these are the only/correct places to make the changes?
> vortex_channel.c(1495): channel->window_size                    =
> 4096;
> vortex_channel.c(1496): channel->seq_no_window
>  = 4096;
> vortex_channel.c(1497): channel->desired_window_size            =
> 4096;
> vortex_channel.c(1503): channel->remote_window                  =
> 4096 ;
> vortex_channel.c(3729): return VORTEX_MIN (remote_buffer_available,
> VORTEX_MIN (channel->window_size, VORTEX_MIN (message_size,  4096 )));
> And, in the following function
> axl_bool      vortex_channel_update_incoming_buffer (VortexChannel *
> channel, 
>     VortexFrame   * frame,
>     unsigned int  * ackno,
>     int           * window)
> below condition has to be modified to send SEQ frames little more
> frequently.
> bytes_available = vortex_channel_incoming_bytes_available (channel,
> frame);
>   if (bytes_available > (channel->seq_no_window / 2)) {
> The text marked in RED are those places to be modified.
> I would reply back to this forum once we perform some tests. 


> If we actually see a performance improvement probably these values can
> be made user configurable so that each user/developer can choose to
> set a value according to his requirement.

You can use the following functions to query/change channel window size

- vortex_channel_set_window_size
- vortex_channel_get_window_size

> Note that I am using vortex version 1.1.8 and hence the line numbers
> mentioned above may not match with the latest code base.

Ok, Cheers!

> Thanks
> Subrahmanya
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> Vortex at lists.aspl.es
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Francis Brosnan Blázquez <francis.brosnan at aspl.es>
91 134 14 22 - 91 134 14 45 - 91 116 07 57


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