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. >
