[ofa-general] ipoib performance (and xplot)

[chas williams - CONTRACTOR]

you capture the transaction with tcpdump and use a perl script
provided with xplot to convert it into something xplot can 
graph.

megabits of course.  so yeah, its pretty awful.  and indeed the recv end
of the tcp connection has saturated the cpu at 100%.  apparently, this
issue is further complicated by my architecture, the ia64.  there doesnt
seem to be an accelerated checksum/copy_to_user.  so the ia64 makes two
passes through the data.  i should have suspected this.

so the xplot graph was right.  the ack's are coming back slow.

thanks!

In message <EXNANE01V6uPDVniSnR00000072 at exnane01.hq.netapp.com>,"Talpey, Thomas
" writes:
>Interesting data. What app are you using to generate the TCP flow,
>and what options are you using on it? Also, what are the scales on
>the x- and y-axes (seconds and decimal kilobytes)? I have some
>comments but they are only speculation without knowing this.
>
>By "800Mb/s" do you megabytes or megabits? For ipoib, 800 megabytes/s
>(MB/s) seems very high and 800 megabits/s (Mb/s) seems very low. In my
>experience it gets 200-300 megabytes before running out of cpu (checksum
>calculations mainly). But I haven't looked at it in a while.
>
>Tom.