Thu, May 16, 2024 at 02:31:59PM CEST, mst@xxxxxxxxxx wrote: >On Thu, May 16, 2024 at 12:54:58PM +0200, Jiri Pirko wrote: >> Thu, May 16, 2024 at 06:48:38AM CEST, jasowang@xxxxxxxxxx wrote: >> >On Wed, May 15, 2024 at 8:54 PM Jiri Pirko <jiri@xxxxxxxxxxx> wrote: >> >> >> >> Wed, May 15, 2024 at 12:12:51PM CEST, jiri@xxxxxxxxxxx wrote: >> >> >Wed, May 15, 2024 at 10:20:04AM CEST, mst@xxxxxxxxxx wrote: >> >> >>On Wed, May 15, 2024 at 09:34:08AM +0200, Jiri Pirko wrote: >> >> >>> Fri, May 10, 2024 at 01:27:08PM CEST, mst@xxxxxxxxxx wrote: >> >> >>> >On Fri, May 10, 2024 at 01:11:49PM +0200, Jiri Pirko wrote: >> >> >>> >> Fri, May 10, 2024 at 12:52:52PM CEST, mst@xxxxxxxxxx wrote: >> >> >>> >> >On Fri, May 10, 2024 at 12:37:15PM +0200, Jiri Pirko wrote: >> >> >>> >> >> Thu, May 09, 2024 at 04:28:12PM CEST, mst@xxxxxxxxxx wrote: >> >> >>> >> >> >On Thu, May 09, 2024 at 03:31:56PM +0200, Jiri Pirko wrote: >> >> >>> >> >> >> Thu, May 09, 2024 at 02:41:39PM CEST, mst@xxxxxxxxxx wrote: >> >> >>> >> >> >> >On Thu, May 09, 2024 at 01:46:15PM +0200, Jiri Pirko wrote: >> >> >>> >> >> >> >> From: Jiri Pirko <jiri@xxxxxxxxxx> >> >> >>> >> >> >> >> >> >> >>> >> >> >> >> Add support for Byte Queue Limits (BQL). >> >> >>> >> >> >> >> >> >> >>> >> >> >> >> Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxx> >> >> >>> >> >> >> > >> >> >>> >> >> >> >Can we get more detail on the benefits you observe etc? >> >> >>> >> >> >> >Thanks! >> >> >>> >> >> >> >> >> >>> >> >> >> More info about the BQL in general is here: >> >> >>> >> >> >> https://lwn.net/Articles/469652/ >> >> >>> >> >> > >> >> >>> >> >> >I know about BQL in general. We discussed BQL for virtio in the past >> >> >>> >> >> >mostly I got the feedback from net core maintainers that it likely won't >> >> >>> >> >> >benefit virtio. >> >> >>> >> >> >> >> >>> >> >> Do you have some link to that, or is it this thread: >> >> >>> >> >> https://lore.kernel.org/netdev/21384cb5-99a6-7431-1039-b356521e1bc3@xxxxxxxxxx/ >> >> >>> >> > >> >> >>> >> > >> >> >>> >> >A quick search on lore turned up this, for example: >> >> >>> >> >https://lore.kernel.org/all/a11eee78-b2a1-3dbc-4821-b5f4bfaae819@xxxxxxxxx/ >> >> >>> >> >> >> >>> >> Says: >> >> >>> >> "Note that NIC with many TX queues make BQL almost useless, only adding extra >> >> >>> >> overhead." >> >> >>> >> >> >> >>> >> But virtio can have one tx queue, I guess that could be quite common >> >> >>> >> configuration in lot of deployments. >> >> >>> > >> >> >>> >Not sure we should worry about performance for these though. >> >> >>> >What I am saying is this should come with some benchmarking >> >> >>> >results. >> >> >>> >> >> >>> I did some measurements with VDPA, backed by ConnectX6dx NIC, single >> >> >>> queue pair: >> >> >>> >> >> >>> super_netperf 200 -H $ip -l 45 -t TCP_STREAM & >> >> >>> nice -n 20 netperf -H $ip -l 10 -t TCP_RR >> >> >>> >> >> >>> RR result with no bql: >> >> >>> 29.95 >> >> >>> 32.74 >> >> >>> 28.77 >> >> >>> >> >> >>> RR result with bql: >> >> >>> 222.98 >> >> >>> 159.81 >> >> >>> 197.88 >> >> >>> >> >> >> >> >> >>Okay. And on the other hand, any measureable degradation with >> >> >>multiqueue and when testing throughput? >> >> > >> >> >With multiqueue it depends if the flows hits the same queue or not. If >> >> >they do, the same results will likely be shown. >> >> >> >> RR 1q, w/o bql: >> >> 29.95 >> >> 32.74 >> >> 28.77 >> >> >> >> RR 1q, with bql: >> >> 222.98 >> >> 159.81 >> >> 197.88 >> >> >> >> RR 4q, w/o bql: >> >> 355.82 >> >> 364.58 >> >> 233.47 >> >> >> >> RR 4q, with bql: >> >> 371.19 >> >> 255.93 >> >> 337.77 >> >> >> >> So answer to your question is: "no measurable degradation with 4 >> >> queues". >> > >> >Thanks but I think we also need benchmarks in cases other than vDPA. >> >For example, a simple virtualization setup. >> >> For virtualization setup, I get this: >> >> VIRT RR 1q, w/0 bql: >> 49.18 >> 49.75 >> 50.07 >> >> VIRT RR 1q, with bql: >> 51.33 >> 47.88 >> 40.40 >> >> No measurable/significant difference. > >Seems the results became much noisier? Also Not enough data to assume that I believe. >I'd expect a regression if any to be in a streaming benchmark. Can you elaborate? > >-- >MST >
