I think better tooling can help and I am always interested in
suggestions on what to add to iperf 2 for better coverages.
I've thought it good for iperf 2 to support some sort of graph which
drives socket read/write/delays vs a simplistic pattern of AFAP. It for
sure stresses things differently, even in drivers. I've seen huge delays
in some 10G drivers where some UDP packets seem to get stuck in queues
and where the e2e latency is driven by the socket write rates vs the
network delays. This is most obvious using burst patterns where the last
packet of a latency burst is coupled to the first packet of the
subsequent burst. The coupling between the syscalls to network
performance is nonobvious and sometimes hard to believe.
We've been adding more "traffic profile" knobs for socket testing and
have much of the latency metrics incorporated. Most don't use these.
They seem to be hard to generalize. Cloudflare seems to have crafted
specific tests after obtaining knowledge of causality.
Bob
PS. As a side note, I'm now being asked how to generate "AI loads" into
switch fabrics, though there it probably won't be based upon socket
syscalls but maybe using io_urings - not sure.
This is good work! I love reading their posts on scale like this.
It’s wild to me that the Linux kernel has (apparently) never
implemented shrinking the receive window, or handling the case of
userspace starting a large transfer and then just not ever reading
it… the latter is less surprising, I guess, because that’s an
application bug that you probably would catch separately, and would be
focused on fixing in the application layer…
-Aaron
On Sat, Jun 3, 2023 at 1:04 AM Dave Taht via Rpm
<r...@lists.bufferbloat.net> wrote:
these folk do good work, and I loved the graphs
https://blog.cloudflare.com/unbounded-memory-usage-by-tcp-for-receive-buffers-and-how-we-fixed-it/
--
Podcast:
https://www.linkedin.com/feed/update/urn:li:activity:7058793910227111937/
Dave Täht CSO, LibreQos
_______________________________________________
Rpm mailing list
r...@lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/rpm
--
- Sent from my iPhone.
_______________________________________________
Rpm mailing list
r...@lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/rpm
_______________________________________________
Bloat mailing list
Bloat@lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/bloat
