From: Jesper Dangaard Brouer <hawk@xxxxxxxxxx> Date: Tue, 26 Nov 2024 18:12:27 +0100 > > > > On 26/11/2024 18.02, Lorenzo Bianconi wrote: >>> From: Daniel Xu <dxu@xxxxxxxxx> >>> Date: Mon, 25 Nov 2024 16:56:49 -0600 >>> >>>> >>>> >>>> On Mon, Nov 25, 2024, at 9:12 AM, Alexander Lobakin wrote: >>>>> From: Daniel Xu <dxu@xxxxxxxxx> >>>>> Date: Fri, 22 Nov 2024 17:10:06 -0700 >>>>> >>>>>> Hi Olek, >>>>>> >>>>>> Here are the results. >>>>>> >>>>>> On Wed, Nov 13, 2024 at 03:39:13PM GMT, Daniel Xu wrote: >>>>>>> >>>>>>> >>>>>>> On Tue, Nov 12, 2024, at 9:43 AM, Alexander Lobakin wrote: >>>>> >>>>> [...] >>>>> >>>>>> Baseline (again) >>>>>> >>>>>> Transactions Latency P50 (s) Latency P90 (s) Latency >>>>>> P99 (s) Throughput (Mbit/s) >>>>>> Run 1 3169917 0.00007295 0.00007871 >>>>>> 0.00009343 Run 1 21749.43 >>>>>> Run 2 3228290 0.00007103 0.00007679 >>>>>> 0.00009215 Run 2 21897.17 >>>>>> Run 3 3226746 0.00007231 0.00007871 >>>>>> 0.00009087 Run 3 21906.82 >>>>>> Run 4 3191258 0.00007231 0.00007743 >>>>>> 0.00009087 Run 4 21155.15 >>>>>> Run 5 3235653 0.00007231 0.00007743 >>>>>> 0.00008703 Run 5 21397.06 >>>>>> Average 3210372.8 0.000072182 0.000077814 >>>>>> 0.00009087 Average 21621.126 >>>>>> >>>>>> cpumap v2 Olek >>>>>> >>>>>> Transactions Latency P50 (s) Latency P90 (s) Latency >>>>>> P99 (s) Throughput (Mbit/s) >>>>>> Run 1 3253651 0.00007167 0.00007807 >>>>>> 0.00009343 Run 1 13497.57 >>>>>> Run 2 3221492 0.00007231 0.00007743 >>>>>> 0.00009087 Run 2 12115.53 >>>>>> Run 3 3296453 0.00007039 0.00007807 >>>>>> 0.00009087 Run 3 12323.38 >>>>>> Run 4 3254460 0.00007167 0.00007807 >>>>>> 0.00009087 Run 4 12901.88 >>>>>> Run 5 3173327 0.00007295 0.00007871 >>>>>> 0.00009215 Run 5 12593.22 >>>>>> Average 3239876.6 0.000071798 0.00007807 >>>>>> 0.000091638 Average 12686.316 >>>>>> Delta 0.92% -0.53% 0.33% >>>>>> 0.85% -41.32% >>>>>> >>>>>> >>>>>> It's very interesting that we see -40% tput w/ the patches. I went >>>>>> back >>>>> >>>>> Oh no, I messed up something =\ >>>>> >>>>> Could you please also test not the whole series, but patches 1-3 >>>>> (up to >>>>> "bpf:cpumap: switch to GRO...") and 1-4 (up to "bpf: cpumap: reuse skb >>>>> array...")? Would be great to see whether this implementation works >>>>> worse right from the start or I just broke something later on. >>>> >>>> Patches 1-3 reproduces the -40% tput numbers. >>> >>> Ok, thanks! Seems like using the hybrid approach (GRO, but on top of >>> cpumap's kthreads instead of NAPI) really performs worse than switching >>> cpumap to NAPI. >>> >>>> >>>> With patches 1-4 the numbers get slightly worse (~1gbps lower) but >>>> it was noisy. >>> >>> Interesting, I was sure patch 4 optimizes stuff... Maybe I'll give up >>> on it. >>> >>>> >>>> tcp_rr results were unaffected. >>> >>> @ Jakub, >>> >>> Looks like I can't just use GRO without Lorenzo's conversion to NAPI, at >>> least for now =\ I took a look on the backlog NAPI and it could be used, >>> although we'd need a pointer in the backlog to the corresponding cpumap >>> + also some synchronization point to make sure backlog NAPI won't access >>> already destroyed cpumap. >>> >>> Maybe Lorenzo could take a look... >> >> it seems to me the only difference would be we will use the shared >> backlog_napi >> kthreads instead of having a dedicated kthread for each cpumap entry >> but we still >> need the napi poll logic. I can look into it if you prefer the shared >> kthread >> approach. > > I don't like a shared kthread approach. For my use-case I want to give > the "remote" CPU-map kthreads higher scheduling priority. (As it will be > running a 2nd XDP BPF DDoS program protecting against overload by > dropping packets). Oh, that is also valid. Let's see what Jakub replies, for now I'm leaning towards posting approach from this RFC with my bulk allocation from the NAPI cache. > > Thus, I'm not a fan of using the shared backlog_napi. As I don't want > to give backlog NAPI high priority, in my use-case. > >> @Jakub: what do you think? > > > --Jesper Thanks, Olek
