On Wed, May 15, 2024 at 09:34:08AM +0200, Jiri Pirko wrote: > 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 >
Okay. And on the other hand, any measureable degradation with multiqueue and when testing throughput? > > > > > > >> > >> > > >> > > >> > > >> > > >> >> 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 > >> >> > > >> > > >
