Fri, May 10, 2024 at 01:27:08PM CEST, m...@redhat.com wrote: >On Fri, May 10, 2024 at 01:11:49PM +0200, Jiri Pirko wrote: >> Fri, May 10, 2024 at 12:52:52PM CEST, m...@redhat.com wrote: >> >On Fri, May 10, 2024 at 12:37:15PM +0200, Jiri Pirko wrote: >> >> Thu, May 09, 2024 at 04:28:12PM CEST, m...@redhat.com wrote: >> >> >On Thu, May 09, 2024 at 03:31:56PM +0200, Jiri Pirko wrote: >> >> >> Thu, May 09, 2024 at 02:41:39PM CEST, m...@redhat.com wrote: >> >> >> >On Thu, May 09, 2024 at 01:46:15PM +0200, Jiri Pirko wrote: >> >> >> >> From: Jiri Pirko <j...@nvidia.com> >> >> >> >> >> >> >> >> Add support for Byte Queue Limits (BQL). >> >> >> >> >> >> >> >> Signed-off-by: Jiri Pirko <j...@nvidia.com> >> >> >> > >> >> >> >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-b356521e1...@redhat.com/ >> > >> > >> >A quick search on lore turned up this, for example: >> >https://lore.kernel.org/all/a11eee78-b2a1-3dbc-4821-b5f4bfaae...@gmail.com/ >> >> 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 > > >> >> > >> > >> > >> > >> >> I don't see why virtio should be any different from other >> >> drivers/devices that benefit from bql. HOL blocking is the same here are >> >> everywhere. >> >> >> >> > >> >> >So I'm asking, what kind of benefit do you observe? >> >> >> >> I don't have measurements at hand, will attach them to v2. >> >> >> >> Thanks! >> >> >> >> > >> >> >-- >> >> >MST >> >> > >> > >
