Jamal Hadi Salim jhs@mojatatu.com writes:
On Tue, Dec 5, 2023 at 1:58 PM Brandeburg, Jesse jesse.brandeburg@intel.com wrote:
Hi everyone,
(regarding the list, the home page is https://lists.netdevconf.info/postorius/lists/net-power.netdevconf.info/)
I think we don’t have a lot of subscribers yet to this list (hey Jamal you should subscribe!)
Already subscribed and pinged other people interested as well.
– invite your power-concerned friends and colleagues.
Toke and I were chatting offline about this problem of power management in networking.
We thought it might be a useful start to figure out a good set of benchmarks to demonstrate “power vs networking” problems. I have a couple in mind right away. One is “system is sleeping but I’m trying to run a latency sensitive workload and the latency sucks” Two is “system is sleeping and my single-threaded bulk throughput benchmark (netperf/iperf2/neper/etc) shows a lot of retransmits and / or receiver drops”
our goal is to collect power use on the _whole system_ for given network bound workloads i.e not just on the CPU side. If we can collect data on how much the NIC is drawing from the PCI bus as well that would be a very useful breakdown. If you have a good understanding of your server maybe that info derived by deduction (collect the power bar draw and subtract what you the CPU uses). Our use case is on offloads: Example, if i can offload TLS on a NIC that draws 45W from the PCI bus vs running the same infra workload on the host which will costs 100W then i can see a clear win on the offload case etc.
I agree, but I don't think this is necessarily limited to offloads. In many cases, the "offload" is just another CPU core that happens to be sitting on the NIC instead of in the host. So absolutely, moving something into an offload can save power, but so can moving it across CPU cores (if it means that some of the now-idle cores can go to sleep). So we need a system for (self-)tuning that can take both into account.
-Toke