On Tue, Oct 31, 2023 at 7:14 AM Sebastian Andrzej Siewior
[off-list ref] wrote:

On 2023-10-16 16:53:39 [+0200], To Jakub Kicinski wrote:

quoted

On 2023-10-16 07:17:56 [-0700], Jakub Kicinski wrote:

quoted

On Mon, 16 Oct 2023 11:53:21 +0200 Sebastian Andrzej Siewior wrote:

quoted

quoted

Do we have reason to believe nobody uses RPS?

Not sure what you relate to. I would assume that RPS is used in general
on actual devices and not on loopback where backlog is used. But it is
just an assumption.
The performance drop, which I observed with RPS and stress-ng --udp, is
within the same range with threads and IPIs (based on memory). I can
re-run the test and provide actual numbers if you want.

I was asking about RPS because with your current series RPS processing
is forced into threads. IDK how well you can simulate the kind of
workload which requires RPS. I've seen it used mostly on proxyies
and gateways. For proxies Meta's experiments with threaded NAPI show
regressions across the board. So "force-threading" RPS will most likely
also cause regressions.

Understood.

Wandere/ Juri: Do you have any benchmark/ workload where you would see
whether RPS with IPI (now) vs RPS (this patch) shows any regression?

So I poked offlist other RH people and I've been told that they hardly
ever test RPS since the NICs these days have RSS in hardware.

Sorry, Juri is in PTO and I am just back from sick leave and still
catching up. I've been contacting some QE people, but so far it is
like you said, no stress test for RPS. If I have some news, I let you
know.

Sebastian