From: rtreffer treffer@measite.de
Some wifi drivers (e.g. ath10k) provide per-station rx/tx values but no estimated throughput. Setting a better estimate than the default 1MBit makes these devices work well with BATMAN V.
Signed-off-by: René Treffer treffer@measite.de --- net/batman-adv/bat_v_elp.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/net/batman-adv/bat_v_elp.c b/net/batman-adv/bat_v_elp.c index 2614a9ca..ce3b52f1 100644 --- a/net/batman-adv/bat_v_elp.c +++ b/net/batman-adv/bat_v_elp.c @@ -68,7 +68,7 @@ static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh) struct ethtool_link_ksettings link_settings; struct net_device *real_netdev; struct station_info sinfo; - u32 throughput; + u32 throughput, rx, tx; int ret;
/* if the user specified a customised value for this interface, then @@ -107,10 +107,25 @@ static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh) } if (ret) goto default_throughput; - if (!(sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT))) - goto default_throughput;
- return sinfo.expected_throughput / 100; + if (sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT)) { + return sinfo.expected_throughput / 100; + } + + // try to estimate en expected throughput based on reported rx/tx rates + // 1/3 of tx or 1/3 of the average of rx and tx, whichever is smaller + if (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE)) { + tx = cfg80211_calculate_bitrate(&sinfo.txrate); + if (sinfo.filled & BIT(NL80211_STA_INFO_RX_BITRATE)) { + rx = cfg80211_calculate_bitrate(&sinfo.rxrate); + if (rx < tx) { + return (rx + tx) / 6; + } + } + return tx / 3; + } + + goto default_throughput; }
/* if not a wifi interface, check if this device provides data via
On Sunday, 9 June 2019 12:19:22 CEST René Treffer wrote:
@@ -107,10 +107,25 @@ static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh) } if (ret) goto default_throughput;
if (!(sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT)))goto default_throughput;return sinfo.expected_throughput / 100;
if (sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT)) {return sinfo.expected_throughput / 100;}// try to estimate en expected throughput based on reported rx/tx rates// 1/3 of tx or 1/3 of the average of rx and tx, whichever is smallerif (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE)) {tx = cfg80211_calculate_bitrate(&sinfo.txrate);if (sinfo.filled & BIT(NL80211_STA_INFO_RX_BITRATE)) {rx = cfg80211_calculate_bitrate(&sinfo.rxrate);if (rx < tx) {return (rx + tx) / 6;}}return tx / 3;}goto default_throughput; } /* if not a wifi interface, check if this device provides data via-- 2.20.1
No, we are not interested in rx rate for tx throughput estimations.
Kind regards, Sven
On Sunday, 9 June 2019 12:19:22 CEST René Treffer wrote:
From: rtreffer treffer@measite.de
Some wifi drivers (e.g. ath10k) provide per-station rx/tx values but no estimated throughput. Setting a better estimate than the default 1MBit makes these devices work well with BATMAN V.
Signed-off-by: René Treffer treffer@measite.de
Please use checkpatch before sending a patch:
WARNING: braces {} are not necessary for single statement blocks #113: FILE: net/batman-adv/bat_v_elp.c:111: + if (sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT)) { + return sinfo.expected_throughput / 100; + }
WARNING: line over 80 characters #117: FILE: net/batman-adv/bat_v_elp.c:115: + // try to estimate en expected throughput based on reported rx/tx rates
WARNING: line over 80 characters #118: FILE: net/batman-adv/bat_v_elp.c:116: + // 1/3 of tx or 1/3 of the average of rx and tx, whichever is smaller
WARNING: braces {} are not necessary for single statement blocks #123: FILE: net/batman-adv/bat_v_elp.c:121: + if (rx < tx) { + return (rx + tx) / 6; + }
WARNING: Missing Signed-off-by: line by nominal patch author 'rtreffer treffer@measite.de'
total: 0 errors, 5 warnings, 0 checks, 36 lines checked
NOTE: For some of the reported defects, checkpatch may be able to mechanically convert to the typical style using --fix or --fix-inplace.
/home/sven/[PATCH] batman-adv_Use wifi rx_tx as fallback throughput.mbox has style problems, please review.
NOTE: If any of the errors are false positives, please report them to the maintainer, see CHECKPATCH in MAINTAINERS
Kind regards, Sven
On Sunday, 9 June 2019 12:19:22 CEST René Treffer wrote:
u32 throughput;
u32 throughput, rx, tx;
Avoid adding multiple variable declarations in a single line. And prefer ordering declarations longest to shortest.
[...]
// try to estimate en expected throughput based on reported rx/tx rates// 1/3 of tx or 1/3 of the average of rx and tx, whichever is smaller
And for the next version of the patch, please also use the same comment style as the rest of the code [1,2].
And please explain also where the magic 1/3 comes from.
Kind regards, Sven
[1] https://www.kernel.org/doc/html/v5.1/process/coding-style.html [2] https://www.kernel.org/doc/Documentation/networking/netdev-FAQ.txt
On Sunday, 9 June 2019 18:37:54 HKT Sven Eckelmann wrote:
No, we are not interested in rx rate for tx throughput estimations.
Before ruling rx out, can you explain your thinking behind this magic formula (if smaller compute sum and divide by 6):
+ if (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE)) { + tx = cfg80211_calculate_bitrate(&sinfo.txrate); + if (sinfo.filled & BIT(NL80211_STA_INFO_RX_BITRATE)) { + rx = cfg80211_calculate_bitrate(&sinfo.rxrate); + if (rx < tx) { + return (rx + tx) / 6; + } + } + return tx / 3; + }
Thanks, Marek
On 09.06.19 13:40, Marek Lindner wrote:
On Sunday, 9 June 2019 18:37:54 HKT Sven Eckelmann wrote:
No, we are not interested in rx rate for tx throughput estimations.
Before ruling rx out, can you explain your thinking behind this magic formula (if smaller compute sum and divide by 6):
Sorry, I should have provided way more context here.... The formula is min(tx/3,avg(rx,tx)/3), which is tx/3 for rx>tx
My thinking was 1. it should be lower than an expected throughput measurement (play it safe) 2. it should still be roughly in line with expected throughput as implemented elsewhere
I am testing this on devices with ath9k (2.4GHz) and ath10k (5GHz), so I was looking at the estimates I get from ath9k. Here is a dump from my home network on 2.4GHz/ath9k and what rx/3 would give us:
signal tx rx expect tx/3 min(tx/3,(rx+tx)/2/3) -77 13.0 43.3 6.682 4.333 -57 130.0 117.0 44.677 43.333 41.166 -53 117.0 130.0 42.388 39.0 -82 43.3 6.5 13.366 14.433 8.3 (!!!) -63 52.0 86.7 26.733 17.333 -58 130.0 173.3 29.21 43.333 !!! -82 6.5 43.3 2.197 2.166 -48 104.0 65.0 40.191 34.666 28.166 -69 57.8 13.0 20.49 19.266 11.8 -58 86.7 52.0 33.507 28.9 23.116 -61 57.8 72.2 29.21 19.266 -42 65.0 72.2 31.218 21.666 -58 52.0 1.0 37.994 17.333 8.833 -56 115.6 144.4 29.21 38.533 !!! -65 39.0 72.2 22.338 13.0 -55 58.5 72.2 29.21 19.5 -65 65.0 72.2 31.218 21.666 -59 86.7 117.0 35.705 28.9 -78 7.2 1.0 4.394 2.4 1.366 -22 65.0 72.2 31.218 21.666 -49 72.2 72.2 33.507 24.066 -68 13.0 21.7 8.879 4.333 -56 52.0 52.0 24.536 17.333 -66 43.3 52.0 24.536 14.433 -63 26.0 39.0 15.563 8.666 -42 65.0 58.5 31.218 21.666 20.583 -60 39.0 26.0 20.49 13.0 10.833 -63 28.9 58.5 17.852 9.633
Cases where the rx/tx estimate would be higher are marked with !!!.
Why bother and look at rx at all? Asymmetric routing should already work. I was bit concerned about highly asymmetric links, especially those where the path back might not work. It might not be worth it though.
Anyway, there are significant over-simplifications in here: - Is what I see here even representative / does it apply universally? - Is 5Ghz and 2.4GHz and their modes even comparable like this? Across drivers/chips?
Regards, René
if (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE)) {tx = cfg80211_calculate_bitrate(&sinfo.txrate);if (sinfo.filled & BIT(NL80211_STA_INFO_RX_BITRATE)) {rx =cfg80211_calculate_bitrate(&sinfo.rxrate);
if (rx < tx) {return (rx + tx) / 6;}}return tx / 3;}Thanks, Marek
On Sunday, 9 June 2019 20:45:06 HKT René Treffer wrote:
I am testing this on devices with ath9k (2.4GHz) and ath10k (5GHz), so I was looking at the estimates I get from ath9k. Here is a dump from my
home network on 2.4GHz/ath9k and what rx/3 would give us:
signal tx rx expect tx/3 min(tx/3,(rx+tx)/2/3) -77 13.0 43.3 6.682 4.333 -57 130.0 117.0 44.677 43.333 41.166 -53 117.0 130.0 42.388 39.0 -82 43.3 6.5 13.366 14.433 8.3 (!!!) -63 52.0 86.7 26.733 17.333 -58 130.0 173.3 29.21 43.333 !!! -82 6.5 43.3 2.197 2.166 -48 104.0 65.0 40.191 34.666 28.166 -69 57.8 13.0 20.49 19.266 11.8 -58 86.7 52.0 33.507 28.9 23.116 -58 52.0 1.0 37.994 17.333 8.833 -56 115.6 144.4 29.21 38.533 !!!
To confirm my understanding: What this table shows are raw tx/rx link estimated values ? None of these numbers compares to Minstrel HT expected throughput or actual throughput ?
Cases where the rx/tx estimate would be higher are marked with !!!.
I also don't quite understand what the '!!!' thing is trying to indicate. What is being compared ? But it may be due to my misunderstandings above.
In my small test setup with one ath10k device meshing with ath9k over 2.4GHz, your tx / 3 formula seems to be quite accurate (had removed the rx part).
# batctl o (your magic formula) * ac:86:74:00:38:06 0.930s ( 45.7) ac:86:74:00:38:06 [ mesh24]
# batctl tp ac:86:74:00:38:06 (actual throughput) Test duration 10440ms. Sent 58393512 Bytes. Throughput: 5.33 MB/s (44.75 Mbps)
What would be interesting is how the numbers produced by 'tx / 3' compare to either the actual throughput (can easily be tested with the throughput meter) or Minstrel expected throughput.
Why bother and look at rx at all? Asymmetric routing should already work. I was bit concerned about highly asymmetric links, especially those where the path back might not work. It might not be worth it though.
Generally, the return path might be entirely different. Batman-adv does not enforce or even endorse symetric paths. If there is better path for the return route, batman-adv will choose the better path based on tx from the sender and if only one return path exists, we don't care anyway ..
Cheers, Marek
Hello, colleagues.
I have a working solution for this problem. It is not batman-related, but I decided to share it with you right here. Please let me clarify some details.
1) Some ath10k firmwares (10.2) do not export tx bitrate. So we can't rely on it. 2) Throughput estimation is better to inject from userspace, rather than make batman estimate it from unreliable sources. 3) Here is the patch for mac80211 We made for ath10k and such drivers that do not export expected throughput value.
I also think it's a better way because a lot of drivers do not work with mac80211 (wil6210). And all driver-dependent math can be easily changed on-the-fly.
Here is simple patch that make possible this expected throughput injection.
--- a/net/mac80211/debugfs_sta.c +++ b/net/mac80211/debugfs_sta.c @@ -12,6 +12,7 @@
#include <linux/debugfs.h> #include <linux/ieee80211.h> +#include <net/mac80211.h> #include "ieee80211_i.h" #include "debugfs.h" #include "debugfs_sta.h" @@ -20,6 +21,8 @@
/* sta attributtes */
+#define DEF_THR_BUFF_SIZE sizeof("4294967295") + #define STA_READ(name, field, format_string) \ static ssize_t sta_ ##name## _read(struct file *file, \ char __user *userbuf, \ @@ -490,6 +493,60 @@ static ssize_t sta_vht_capa_read(struct STA_OPS(vht_capa);
+static ssize_t sta_def_thr_read(struct file *file, char __user *userbuf, + size_t count, loff_t *ppos) +{ + int ret = 0; + char buf[DEF_THR_BUFF_SIZE] = { 0 }; + struct sta_info *sta = file->private_data; + + rcu_read_lock(); + + // Access synchronization to struct sta_info is documented in net/mac80211/sta_info.c:34 + ret = snprintf(buf, DEF_THR_BUFF_SIZE - 1, "%u", sta->def_thr); + + rcu_read_unlock(); + + if(ret >= DEF_THR_BUFF_SIZE) + return -EFAULT; + + buf[DEF_THR_BUFF_SIZE - 1] = '\0'; + + return simple_read_from_buffer(userbuf, count, ppos, buf, ret); +} + +static ssize_t sta_def_thr_write(struct file *file, const char __user *userbuf, + size_t count, loff_t *ppos) +{ + u32 thr = 0; + int ret = 0; + char buf[DEF_THR_BUFF_SIZE] = { 0 }; + struct sta_info *sta = file->private_data; + + if(count >= DEF_THR_BUFF_SIZE) + return -EINVAL; + + if (copy_from_user(buf, userbuf, count)) + return -EFAULT; + + buf[DEF_THR_BUFF_SIZE - 1] = '\0'; + + ret = sscanf(buf, "%u", &thr); + if(ret != 1) + return -EINVAL; + + rcu_read_lock(); + + // Access synchronization to struct sta_info is documented in net/mac80211/sta_info.c:34 + sta->def_thr = thr; + ieee80211_sta_set_expected_throughput(&sta->sta, thr); + + rcu_read_unlock(); + + return count; +} +STA_OPS_RW(def_thr); + #define DEBUGFS_ADD(name) \ debugfs_create_file(#name, 0400, \ sta->debugfs_dir, sta, &sta_ ##name## _ops); @@ -534,6 +591,7 @@ void ieee80211_sta_debugfs_add(struct st DEBUGFS_ADD(agg_status); DEBUGFS_ADD(ht_capa); DEBUGFS_ADD(vht_capa); + DEBUGFS_ADD(def_thr);
DEBUGFS_ADD_COUNTER(rx_duplicates, rx_stats.num_duplicates); DEBUGFS_ADD_COUNTER(rx_fragments, rx_stats.fragments); --- a/net/mac80211/sta_info.c +++ b/net/mac80211/sta_info.c @@ -2305,6 +2305,9 @@ u32 sta_get_expected_throughput(struct s else thr = drv_get_expected_throughput(local, sta);
+ if(thr == 0 && sta->def_thr != 0) + thr = sta->def_thr; + return thr; }
--- b/net/mac80211/sta_info.h +++ a/net/mac80211/sta_info.h @@ -509,6 +509,7 @@ struct work_struct drv_deliver_wk;
u16 listen_interval; + u32 def_thr;
bool dead; bool removed;
Best Regards, Lukonin Kirill
пн, 10 июн. 2019 г. в 08:32, Marek Lindner mareklindner@neomailbox.ch:
On Sunday, 9 June 2019 20:45:06 HKT René Treffer wrote:
I am testing this on devices with ath9k (2.4GHz) and ath10k (5GHz), so I was looking at the estimates I get from ath9k. Here is a dump from my
home network on 2.4GHz/ath9k and what rx/3 would give us:
signal tx rx expect tx/3 min(tx/3,(rx+tx)/2/3) -77 13.0 43.3 6.682 4.333 -57 130.0 117.0 44.677 43.333 41.166 -53 117.0 130.0 42.388 39.0 -82 43.3 6.5 13.366 14.433 8.3 (!!!) -63 52.0 86.7 26.733 17.333 -58 130.0 173.3 29.21 43.333 !!! -82 6.5 43.3 2.197 2.166 -48 104.0 65.0 40.191 34.666 28.166 -69 57.8 13.0 20.49 19.266 11.8 -58 86.7 52.0 33.507 28.9 23.116 -58 52.0 1.0 37.994 17.333 8.833 -56 115.6 144.4 29.21 38.533 !!!
To confirm my understanding: What this table shows are raw tx/rx link estimated values ? None of these numbers compares to Minstrel HT expected throughput or actual throughput ?
Cases where the rx/tx estimate would be higher are marked with !!!.
I also don't quite understand what the '!!!' thing is trying to indicate. What is being compared ? But it may be due to my misunderstandings above.
In my small test setup with one ath10k device meshing with ath9k over 2.4GHz, your tx / 3 formula seems to be quite accurate (had removed the rx part).
# batctl o (your magic formula)
- ac:86:74:00:38:06 0.930s ( 45.7) ac:86:74:00:38:06 [ mesh24]
# batctl tp ac:86:74:00:38:06 (actual throughput) Test duration 10440ms. Sent 58393512 Bytes. Throughput: 5.33 MB/s (44.75 Mbps)
What would be interesting is how the numbers produced by 'tx / 3' compare to either the actual throughput (can easily be tested with the throughput meter) or Minstrel expected throughput.
Why bother and look at rx at all? Asymmetric routing should already work. I was bit concerned about highly asymmetric links, especially those where the path back might not work. It might not be worth it though.
Generally, the return path might be entirely different. Batman-adv does not enforce or even endorse symetric paths. If there is better path for the return route, batman-adv will choose the better path based on tx from the sender and if only one return path exists, we don't care anyway ..
Cheers, Marek
On 10.06.19 05:31, Marek Lindner wrote:
On Sunday, 9 June 2019 20:45:06 HKT René Treffer wrote:
I am testing this on devices with ath9k (2.4GHz) and ath10k (5GHz), so I was looking at the estimates I get from ath9k. Here is a dump from my
home network on 2.4GHz/ath9k and what rx/3 would give us:
signal tx rx expect tx/3 min(tx/3,(rx+tx)/2/3) -77 13.0 43.3 6.682 4.333 -57 130.0 117.0 44.677 43.333 41.166 -53 117.0 130.0 42.388 39.0 -82 43.3 6.5 13.366 14.433 8.3 (!!!) -63 52.0 86.7 26.733 17.333 -58 130.0 173.3 29.21 43.333 !!! -82 6.5 43.3 2.197 2.166 -48 104.0 65.0 40.191 34.666 28.166 -69 57.8 13.0 20.49 19.266 11.8 -58 86.7 52.0 33.507 28.9 23.116 -58 52.0 1.0 37.994 17.333 8.833 -56 115.6 144.4 29.21 38.533 !!!
To confirm my understanding: What this table shows are raw tx/rx link estimated values ? None of these numbers compares to Minstrel HT expected throughput or actual throughput ?
Ah sorry, _expect_ is the current ath9k expected throughput and that should be minstrel, right? I pulled data from my ath9k devices, e.g.
# iw dev wlan1 station dump Station e8:de:27:70:0e:bd (on wlan1) [...] signal: -56 [-59, -59, -80] dBm tx bitrate: 117.0 MBit/s MCS 20 rx bitrate: 144.4 MBit/s MCS 15 short GI expected throughput: 42.388Mbps [...]
Those are the potential inputs (-56, 117, 144.4) and a desired output (42.388), or as a table
signal tx rx expect -56 117.0 144.4 42.388
I then computed manually the tx/3 (39.0) which is lower than (rx+tx)/2/3. The full line would be
signal tx rx expect tx/3 min(tx/3,(rx+tx)/2/3) -56 117.0 144.4 42.388 39.0
I hope this makes sense now. I wanted to get close to the current throughput estimation with worse inputs. I would be happy to check more inputs, but the tx/3 turned out to be pretty close and usually slightly lower.
Cases where the rx/tx estimate would be higher are marked with !!!.
I also don't quite understand what the '!!!' thing is trying to indicate. What is being compared ? But it may be due to my misunderstandings above.
I haven't done an actual throughput test, and I would expect the outputs of my heuristic to be worse. So I wanted to give slightly lower values than the expected throughput.
The other way to think about it: if you were to replace the expected_throughput input where would you over-estimate the link quality now?
In my small test setup with one ath10k device meshing with ath9k over 2.4GHz, your tx / 3 formula seems to be quite accurate (had removed the rx part).
# batctl o (your magic formula)
- ac:86:74:00:38:06 0.930s ( 45.7) ac:86:74:00:38:06 [ mesh24]
# batctl tp ac:86:74:00:38:06 (actual throughput) Test duration 10440ms. Sent 58393512 Bytes. Throughput: 5.33 MB/s (44.75 Mbps)
What would be interesting is how the numbers produced by 'tx / 3' compare to either the actual throughput (can easily be tested with the throughput meter) or Minstrel expected throughput.
Comparing with actual throughput sounds like a good idea, I'll do that next. Right now I don't know how well estimates on both radios hold and how well they are comparable.
Why bother and look at rx at all? Asymmetric routing should already work. I was bit concerned about highly asymmetric links, especially those where the path back might not work. It might not be worth it though.
Generally, the return path might be entirely different. Batman-adv does not enforce or even endorse symetric paths. If there is better path for the return route, batman-adv will choose the better path based on tx from the sender and if only one return path exists, we don't care anyway ..
Cheers, Marek
Hi,
I have a working solution for this problem. It is not batman-related, but I decided to share it with you right here. Please let me clarify some details.
- Some ath10k firmwares (10.2) do not export tx bitrate. So we can't
rely on it. 2) Throughput estimation is better to inject from userspace, rather than make batman estimate it from unreliable sources. 3) Here is the patch for mac80211 We made for ath10k and such drivers that do not export expected throughput value.
you are very right about those issues. However, your patch only provides a quick way to push an arbitrary throughput metric into the batman-adv kernel module. The current discussion is about how such metric could be best derived in an automated fashion.
Would you mind sharing your approach to obtaining such a metric that addresses the problems mentioned above ?
Thanks, Marek
ср, 12 июн. 2019 г. в 11:39, Marek Lindner mareklindner@neomailbox.ch:
Hi,
I have a working solution for this problem. It is not batman-related, but I decided to share it with you right here. Please let me clarify some details.
- Some ath10k firmwares (10.2) do not export tx bitrate. So we can't
rely on it. 2) Throughput estimation is better to inject from userspace, rather than make batman estimate it from unreliable sources. 3) Here is the patch for mac80211 We made for ath10k and such drivers that do not export expected throughput value.
you are very right about those issues. However, your patch only provides a quick way to push an arbitrary throughput metric into the batman-adv kernel module. The current discussion is about how such metric could be best derived in an automated fashion.
Would you mind sharing your approach to obtaining such a metric that addresses the problems mentioned above ?
Thanks, Marek
Yes, sure.
I can't share a source code because it partially belongs to one commercial company. But I want and I can share my ideas with empirical evidence. Also I will be very glad to help Batman-avd mesh community and become a part of it.
So here is the algorithm. It has a structure we call matryoshka. ET - Expected_throughput.
1) ET = TX_bitrate * Transmit_probability * Overhead_coefficient Transmit_probability is always less than 1 so Expected throughput can't be equal to the TX_bitrate. Overhead_coefficient is also should be less than 1
2) Transmit_probability = 1 - Retry_probability - Error_probability
3) Retry_probability = TX_retries / TX_packets
4) Error_probability = TX_errors / TX_packets
5) Overhead_coefficient for 802.11 is fair enough to be 0.65, but can be changed after additional testing.
ET = TX_bitrate * (1 - (TX_retries + TX_errors) / TX_packets) * 0.65 Such technique has very large hysteresis which is good to avoid flapping between different nodes. In my MESH lab this formula works quite well. Please ask any questions and feel free to criticize.
Also please note that ath10k tx_bitrate can be fetched from ath10k firmware debugfs statistics. Even with 10.2 firmware.
Best Regards, Lukonin Kirill
On Thursday, 13 June 2019 04:50:44 HKT Кирилл Луконин wrote:
So here is the algorithm. It has a structure we call matryoshka. ET - Expected_throughput.
- ET = TX_bitrate * Transmit_probability * Overhead_coefficient
Transmit_probability is always less than 1 so Expected throughput can't be equal to the TX_bitrate. Overhead_coefficient is also should be less than 1
Transmit_probability = 1 - Retry_probability - Error_probability
Retry_probability = TX_retries / TX_packets
Error_probability = TX_errors / TX_packets
Overhead_coefficient for 802.11 is fair enough to be 0.65, but can
be changed after additional testing.
ET = TX_bitrate * (1 - (TX_retries + TX_errors) / TX_packets) * 0.65 Such technique has very large hysteresis which is good to avoid flapping between different nodes. In my MESH lab this formula works quite well.
This looks like an interesting approach. Which chips / environments did you test this formula with and how did the result compare to the actual TCP throughput ?
Thanks, Marek
Hello, Marek.
On Thursday, 13 June 2019 04:50:44 HKT Кирилл Луконин wrote:
So here is the algorithm. It has a structure we call matryoshka. ET - Expected_throughput.
- ET = TX_bitrate * Transmit_probability * Overhead_coefficient
Transmit_probability is always less than 1 so Expected throughput can't be equal to the TX_bitrate. Overhead_coefficient is also should be less than 1
Transmit_probability = 1 - Retry_probability - Error_probability
Retry_probability = TX_retries / TX_packets
Error_probability = TX_errors / TX_packets
Overhead_coefficient for 802.11 is fair enough to be 0.65, but can
be changed after additional testing.
ET = TX_bitrate * (1 - (TX_retries + TX_errors) / TX_packets) * 0.65 Such technique has very large hysteresis which is good to avoid flapping between different nodes. In my MESH lab this formula works quite well.
This looks like an interesting approach. Which chips / environments did you test this formula with and how did the result compare to the actual TCP throughput ?
Thanks, Marek
Mostly QCA988x was tested. Sorry, I lost my test results so I need to do it again. I have UBNT AC MESH, UBNT AP AC Lite and TP-Link RE450 in my lab.
Also, as I think, it's better to test UDP throughput, But I can test both TCP and UDP. This formula always show a result that close to UDP throughput. So, may be we can think about additional parameters/coefficients that depend on protocols or something else.
Best Regards, Lukonin Kirill
вт, 25 июн. 2019 г. в 13:26, Marek Lindner mareklindner@neomailbox.ch:
On Thursday, 13 June 2019 04:50:44 HKT Кирилл Луконин wrote:
So here is the algorithm. It has a structure we call matryoshka. ET - Expected_throughput.
- ET = TX_bitrate * Transmit_probability * Overhead_coefficient
Transmit_probability is always less than 1 so Expected throughput can't be equal to the TX_bitrate. Overhead_coefficient is also should be less than 1
Transmit_probability = 1 - Retry_probability - Error_probability
Retry_probability = TX_retries / TX_packets
Error_probability = TX_errors / TX_packets
Overhead_coefficient for 802.11 is fair enough to be 0.65, but can
be changed after additional testing.
ET = TX_bitrate * (1 - (TX_retries + TX_errors) / TX_packets) * 0.65 Such technique has very large hysteresis which is good to avoid flapping between different nodes. In my MESH lab this formula works quite well.
This looks like an interesting approach. Which chips / environments did you test this formula with and how did the result compare to the actual TCP throughput ?
Thanks, Marek
On Thursday, 27 June 2019 18:41:54 HKT Кирилл Луконин wrote:
Mostly QCA988x was tested. Sorry, I lost my test results so I need to do it again. I have UBNT AC MESH, UBNT AP AC Lite and TP-Link RE450 in my lab.
It'd be great to see those numbers.
Also, as I think, it's better to test UDP throughput, But I can test both TCP and UDP. This formula always show a result that close to UDP throughput. So, may be we can think about additional parameters/coefficients that depend on protocols or something else.
Why is UDP better ? The thinking behind comparing to TCP throughput is that most applications use TCP and not UDP.
Cheers, Marek
On Monday, 10 June 2019 18:06:23 HKT René Treffer wrote:
I also don't quite understand what the '!!!' thing is trying to indicate. What is being compared ? But it may be due to my misunderstandings above.
I haven't done an actual throughput test, and I would expect the outputs of my heuristic to be worse. So I wanted to give slightly lower values than the expected throughput.
The other way to think about it: if you were to replace the expected_throughput input where would you over-estimate the link quality now?
Sorry, I don't follow that train of thought. Due to the lack of numbers comparing the magic formula (tx /3) with actual throughput we (Antonio and I) ran a few tests on ath10k devices using your patch. Surprising to us, this approach worked quite well.
I will re-post your patch as RFC to encourage others to test the resulting B.A.T.M.A.N. V routing decisions. If you happen to have tested more on your end, please share your results.
Also, why considering rx on top of tx still isn't clear. Could you explain some more ?
Thanks, Marek
b.a.t.m.a.n@lists.open-mesh.org
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Marek Lindner -
René Treffer -
Sven Eckelmann -
Кирилл Луконин