[Make-wifi-fast] [PATCH] ath10k: snoc: enable threaded napi on WCN3990
Bob McMahon
bob.mcmahon at broadcom.com
Fri Dec 30 15:41:03 EST 2022
FYI, we're trying to add "simple" responsiveness features to the 2.1.9
release. Industry input is appreciated. We've done a lot of one way delay
work as well as different traffic profiles.
I'm at a stage of trying to show Broadcom mgmt that releasing iperf 2 as
open source to skilled network engineers will enable the networking
industry (& the best network silicon providers) in the entire e2e path.
Some questions I get are:
- Who really uses it?
- Why can't other open source or commercially provided tools be used?
- Why don't others help out much with the open source effort?
- What are the key performance indicators that will influence engineers
in the industry in an actionable way?
- What are the futures per the networking community, e.g. test support
for UDP QUIC?
Thanks,
Bob
Bob
On Thu, Dec 29, 2022 at 7:44 PM Dave Taht <dave.taht at gmail.com> wrote:
> thx for leaning in bob! (for those of you that don't know, he's the
> iperf2 maintainer, and if you haven't updated your distro/os/test
> environment to 2.1.8 that came out in august, yet there's all kinds of
> nifty new stuff in there: https://sourceforge.net/projects/iperf2 -
> too much to list, and the -i 1 -e option is just the start of it....
>
> Iperf2's principal flaw is that people think iperf3 is the successor
> to it, and no, they are very different codebases, with very different
> features. iperf = iperf2, for most, but not all.
>
> On Wed, Dec 28, 2022 at 9:54 PM Bob McMahon <bob.mcmahon at broadcom.com>
> wrote:
> >
> > A bit of a tangent but iperf 2's enhanced option provides sampled RTT
> and CWND in the interval output. I requires -e. It also provide the connect
> time, the icwnd, irtt and the mss per the connect.
> >
> > [rjmcmahon at rjm-nas ~]$ iperf -c 192.168.1.85 -i 1 -e
> > ------------------------------------------------------------
> > Client connecting to 192.168.1.85, TCP port 5001 with pid 20041 (1 flows)
> > Write buffer size: 131072 Byte
> > TOS set to 0x0 (Nagle on)
> > TCP window size: 16.0 KByte (default)
> > ------------------------------------------------------------
> > [ 1] local 192.168.1.73%eno1 port 38822 connected with 192.168.1.85
> port 5001 (sock=3) (icwnd/mss/irtt=14/1448/246) (ct=0.32 ms) on 2022-12-28
> 21:51:13 (PST)
> > [ ID] Interval Transfer Bandwidth Write/Err Rtry
> Cwnd/RTT(var) NetPwr
> > [ 1] 0.00-1.00 sec 114 MBytes 952 Mbits/sec 908/0 3
> 353K/1901(59) us 62606
> > [ 1] 1.00-2.00 sec 111 MBytes 932 Mbits/sec 889/0 0
> 354K/2029(115) us 57429
> > [ 1] 2.00-3.00 sec 112 MBytes 937 Mbits/sec 894/0 3
> 354K/2061(84) us 56855
> > [ 1] 3.00-4.00 sec 112 MBytes 938 Mbits/sec 895/0 3
> 354K/2027(115) us 57873
> > [ 1] 4.00-5.00 sec 112 MBytes 938 Mbits/sec 895/0 6
> 354K/2046(68) us 57336
> > [ 1] 5.00-6.00 sec 112 MBytes 937 Mbits/sec 894/0 0
> 374K/2160(109) us 54249
> > [ 1] 6.00-7.00 sec 111 MBytes 933 Mbits/sec 890/0 2
> 374K/2155(115) us 54132
> > [ 1] 7.00-8.00 sec 111 MBytes 934 Mbits/sec 891/0 2
> 374K/2139(120) us 54598
> > [ 1] 8.00-9.00 sec 112 MBytes 938 Mbits/sec 895/0 0
> 374K/2129(126) us 55101
> > [ 1] 9.00-10.00 sec 112 MBytes 935 Mbits/sec 892/0 1
> 374K/2200(102) us 53144
> > [ 1] 0.00-10.03 sec 1.09 GBytes 935 Mbits/sec 8944/0 20
> 374K/4082(4010) us 28632
>
> This is a wonderful new feature, much simpler than relying on packet
> captures. However! this test result above is on a decent, ethernet,
> network, where on wifi, or anything bufferbloated, you would see the
> cwnd and rtt inflate and/or bounce around horribly.
>
>
> >
> >
> > Bob
> >
> > On Wed, Dec 28, 2022 at 4:49 PM Dave Taht via Make-wifi-fast <
> make-wifi-fast at lists.bufferbloat.net> wrote:
> >>
> >> On Wed, Dec 28, 2022 at 3:53 PM Abhishek Kumar <kuabhs at chromium.org>
> wrote:
> >> >
> >> > Apologies for the late reply, Thanks Dave for your comment. My answer
> is inline.
> >> >
> >> > On Tue, Dec 20, 2022 at 7:10 AM Dave Taht <dave.taht at gmail.com>
> wrote:
> >> > >
> >> > > I am always interested in flent.org tcp_nup, tcp_ndown, and rrul_be
> >> > > tests on wifi hardware. In AP mode, especially, against a few
> clients
> >> > > in rtt_fair on the "ending the anomaly" test suite at the bottom of
> >> > > this link: https://www.cs.kau.se/tohojo/airtime-fairness/ . Of
> these,
> >> > > it's trying to optimize bandwidth more fairly and keep latencies low
> >> > > when 4 or more stations are trying to transmit (in a world with 16
> or
> >> > > more stations online), that increasingly bothers me the most. I'm
> >> > > seeing 5+ seconds on some rtt_fair-like tests nowadays.
> >> > I used testing using iperf and conductive setup and fetched the
> >> > throughput data(mentioned below).
> >> > >
> >> > > I was also seeing huge simultaneous upload vs download disparities
> on
> >> > > the latest kernels, on various threads over here:
> >> > > https://forum.openwrt.org/t/aql-and-the-ath10k-is-lovely/59002 and
> >> > > more recently here:
> >> > >
> https://forum.openwrt.org/t/reducing-multiplexing-latencies-still-further-in-wifi/133605
> >> > Interesting, thanks for the pointer and probably the Qualcomm team is
> >> > aware of it.
> >> > >
> >> > > I don't understand why napi with the default budget (64) is even
> >> > > needed on the ath10k, as a single txop takes a minimum of ~200us,
> but
> >> > > perhaps your patch will help. Still, measuring the TCP statistics
> >> > > in-band would be nice to see. Some new tools are appearing that can
> do
> >> > > this, Apple's goresponsiveness, crusader... that are simpler to use
> >> > > than flent.
> >> > Here are some of the additional raw data with and without threaded
> napi:
> >> > ==================================================
> >> > udp_rx(Without threaded NAPI)
> >> > 435.98+-5.16 : Channel 44
> >> > 439.06+-0.66 : Channel 157
> >> >
> >> > udp_rx(With threaded NAPI)
> >> > 509.73+-41.03 : Channel 44
> >> > 549.97+-7.62 : Channel 157
> >> > ===================================================
> >> > udp_tx(Without threaded NAPI)
> >> > 461.31+-0.69 : Channel 44
> >> > 461.46+-0.78 : Channel 157
> >> >
> >> > udp_tx(With threaded NAPI)
> >> > 459.20+-0.77 : Channel 44
> >> > 459.78+-1.08 : Channel 157
> >> > ===================================================
> >> > tcp_rx(Without threaded NAPI)
> >> > 472.63+-2.35 : Channel 44
> >> > 469.29+-6.31 : Channel 157
> >> >
> >> > tcp_rx(With threaded NAPI)
> >> > 498.49+-2.44 : Channel 44
> >> > 541.14+-40.65 : Channel 157
> >> > ===================================================
> >> > tcp_tx(Without threaded NAPI)
> >> > 317.34+-2.37 : Channel 44
> >> > 317.01+-2.56 : Channel 157
> >> >
> >> > tcp_tx(With threaded NAPI)
> >> > 371.34+-2.36 : Channel 44
> >> > 376.95+-9.40 : Channel 157
> >>
> >> My concern is primarily with the induced tcp latency on this test. A
> >> way to check that is to run wireshark on your test client driving the
> >> test, capture the iperf traffic, and then plot the "Statistics->TCP
> >> stream statistics for both throughput and rtt. Would it be possible
> >> for you to do that and put up those plots somewhere?
> >>
> >> The worst case test is a tcp bidirectional test which I don't know if
> >> older iperfs can do. (iperf2 has new bounceback and bidir tests)
> >>
> >> Ideally stuff going in either direction, would not look as horrible,
> >> as it did, back in 2016, documented in this linuxplumbers presentation
> >> here:
> https://blog.linuxplumbersconf.org/2016/ocw/system/presentations/3963/original/linuxplumbers_wifi_latency-3Nov.pdf
> >> and discussed on lwn, here: https://lwn.net/Articles/705884/
> >>
> >> I worry about folk achieving slightly better tcp throughput at the
> >> expense of clobbering in-tcp-stream latency. Back then we were
> >> shooting for no more than 40ms extra latency under load on this chip,
> >> down from (unusable) seconds. Presently elsewhere, on other chips,
> >> we're getting 8ms with stuff that's not in tree for the ath10k, there
> >> is a slight cost in single stream throughput but when multiple streams
> >> are in use, on multiple stations, things like web pages fly,
> >> irrespective of load.
> >>
> >>
> >> > ====================================================
> >> >
> >> > >
> >> > > On Tue, Dec 20, 2022 at 12:17 AM Abhishek Kumar <
> kuabhs at chromium.org> wrote:
> >> > > >
> >> > > > NAPI poll can be done in threaded context along with soft irq
> >> > > > context. Threaded context can be scheduled efficiently, thus
> >> > > > creating less of bottleneck during Rx processing. This patch is
> >> > > > to enable threaded NAPI on ath10k driver.
> >> > > >
> >> > > > Based on testing, it was observed that on WCN3990, the CPU0
> reaches
> >> > > > 100% utilization when napi runs in softirq context. At the same
> >> > > > time the other CPUs are at low consumption percentage. This
> >> > > > does not allow device to reach its maximum throughput potential.
> >> > > > After enabling threaded napi, CPU load is balanced across all CPUs
> >> > > > and following improvments were observed:
> >> > > > - UDP_RX increase by ~22-25%
> >> > > > - TCP_RX increase by ~15%
> >> > > >
> >> > > > Tested-on: WCN3990 hw1.0 SNOC WLAN.HL.3.2.2-00696-QCAHLSWMTPL-1
> >> > > > Signed-off-by: Abhishek Kumar <kuabhs at chromium.org>
> >> > > > ---
> >> > > >
> >> > > > drivers/net/wireless/ath/ath10k/core.c | 16 ++++++++++++++++
> >> > > > drivers/net/wireless/ath/ath10k/hw.h | 2 ++
> >> > > > drivers/net/wireless/ath/ath10k/snoc.c | 3 +++
> >> > > > 3 files changed, 21 insertions(+)
> >> > > >
> >> > > > diff --git a/drivers/net/wireless/ath/ath10k/core.c
> b/drivers/net/wireless/ath/ath10k/core.c
> >> > > > index 5eb131ab916fd..ee4b6ba508c81 100644
> >> > > > --- a/drivers/net/wireless/ath/ath10k/core.c
> >> > > > +++ b/drivers/net/wireless/ath/ath10k/core.c
> >> > > > @@ -100,6 +100,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA988X_HW_2_0_VERSION,
> >> > > > @@ -140,6 +141,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA9887_HW_1_0_VERSION,
> >> > > > @@ -181,6 +183,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA6174_HW_3_2_VERSION,
> >> > > > @@ -217,6 +220,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA6174_HW_2_1_VERSION,
> >> > > > @@ -257,6 +261,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA6174_HW_2_1_VERSION,
> >> > > > @@ -297,6 +302,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA6174_HW_3_0_VERSION,
> >> > > > @@ -337,6 +343,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA6174_HW_3_2_VERSION,
> >> > > > @@ -381,6 +388,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA99X0_HW_2_0_DEV_VERSION,
> >> > > > @@ -427,6 +435,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA9984_HW_1_0_DEV_VERSION,
> >> > > > @@ -480,6 +489,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA9888_HW_2_0_DEV_VERSION,
> >> > > > @@ -530,6 +540,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA9377_HW_1_0_DEV_VERSION,
> >> > > > @@ -570,6 +581,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA9377_HW_1_1_DEV_VERSION,
> >> > > > @@ -612,6 +624,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA9377_HW_1_1_DEV_VERSION,
> >> > > > @@ -645,6 +658,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = QCA4019_HW_1_0_DEV_VERSION,
> >> > > > @@ -692,6 +706,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = false,
> >> > > > .use_fw_tx_credits = true,
> >> > > > .delay_unmap_buffer = false,
> >> > > > + .enable_threaded_napi = false,
> >> > > > },
> >> > > > {
> >> > > > .id = WCN3990_HW_1_0_DEV_VERSION,
> >> > > > @@ -725,6 +740,7 @@ static const struct ath10k_hw_params
> ath10k_hw_params_list[] = {
> >> > > > .hw_restart_disconnect = true,
> >> > > > .use_fw_tx_credits = false,
> >> > > > .delay_unmap_buffer = true,
> >> > > > + .enable_threaded_napi = true,
> >> > > > },
> >> > > > };
> >> > > >
> >> > > > diff --git a/drivers/net/wireless/ath/ath10k/hw.h
> b/drivers/net/wireless/ath/ath10k/hw.h
> >> > > > index 9643031a4427a..adf3076b96503 100644
> >> > > > --- a/drivers/net/wireless/ath/ath10k/hw.h
> >> > > > +++ b/drivers/net/wireless/ath/ath10k/hw.h
> >> > > > @@ -639,6 +639,8 @@ struct ath10k_hw_params {
> >> > > > bool use_fw_tx_credits;
> >> > > >
> >> > > > bool delay_unmap_buffer;
> >> > > > +
> >> > > > + bool enable_threaded_napi;
> >> > > > };
> >> > > >
> >> > > > struct htt_resp;
> >> > > > diff --git a/drivers/net/wireless/ath/ath10k/snoc.c
> b/drivers/net/wireless/ath/ath10k/snoc.c
> >> > > > index cfcb759a87dea..b94150fb6ef06 100644
> >> > > > --- a/drivers/net/wireless/ath/ath10k/snoc.c
> >> > > > +++ b/drivers/net/wireless/ath/ath10k/snoc.c
> >> > > > @@ -927,6 +927,9 @@ static int ath10k_snoc_hif_start(struct
> ath10k *ar)
> >> > > >
> >> > > > bitmap_clear(ar_snoc->pending_ce_irqs, 0, CE_COUNT_MAX);
> >> > > >
> >> > > > + if (ar->hw_params.enable_threaded_napi)
> >> > > > + dev_set_threaded(&ar->napi_dev, true);
> >> > > > +
> >> > > > ath10k_core_napi_enable(ar);
> >> > > > ath10k_snoc_irq_enable(ar);
> >> > > > ath10k_snoc_rx_post(ar);
> >> > > > --
> >> > > > 2.39.0.314.g84b9a713c41-goog
> >> > > >
> >> > >
> >> > >
> >> > > --
> >> > > This song goes out to all the folk that thought Stadia would work:
> >> > >
> https://www.linkedin.com/posts/dtaht_the-mushroom-song-activity-6981366665607352320-FXtz
> >> > > Dave Täht CEO, TekLibre, LLC
> >>
> >>
> >>
> >> --
> >> This song goes out to all the folk that thought Stadia would work:
> >>
> https://www.linkedin.com/posts/dtaht_the-mushroom-song-activity-6981366665607352320-FXtz
> >> Dave Täht CEO, TekLibre, LLC
> >> _______________________________________________
> >> Make-wifi-fast mailing list
> >> Make-wifi-fast at lists.bufferbloat.net
> >> https://lists.bufferbloat.net/listinfo/make-wifi-fast
> >
> >
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> --
> This song goes out to all the folk that thought Stadia would work:
>
> https://www.linkedin.com/posts/dtaht_the-mushroom-song-activity-6981366665607352320-FXtz
> Dave Täht CEO, TekLibre, LLC
>
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