Post AyvlMPUPcFthHiPwGW by Suiseiseki@freesoftwareextremist.com
(DIR) More posts by Suiseiseki@freesoftwareextremist.com
(DIR) Post #AyuVbDEreZzbD0DnMm by wolf480pl@mstdn.io
2025-10-05T20:46:43Z
1 likes, 0 repeats
If you're sshing to something that's connected over wifiand it feels as if you were ssh-ing to another continent... from a traindo yourself a favor and, on the remote end, set this:iw dev wlan0 set power_save off
(DIR) Post #AyuW9KacpT5xqxfXQ8 by wolf480pl@mstdn.io
2025-10-05T20:52:54Z
1 likes, 0 repeats
I totally didn't just lose 2 hours chasing ghosts, comparing kernel logs, changing wifi channels, and turning off devices that might cause interference, due to not knowing about this feature.
(DIR) Post #AyuZ9x7drkCHDq6HCa by amonakov@mastodon.gamedev.place
2025-10-05T21:26:35Z
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@wolf480pl I think it shouldn't be that bad? On my old laptop power_save is disabled by default, as I recall, due to known issues, on the new laptop I never noticed any problems (and, as I just checked, it is enabled by default).
(DIR) Post #AyuZuq02AKOqk3tkR6 by wolf480pl@mstdn.io
2025-10-05T21:35:06Z
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@amonakov ping from router to my laptopwith powersave on:30-200ms (highly variable)with powersave off:1.5-4ms, usually below 2.1on a Lenovo mini-PC with QCA6174 (ath10k) I was getting up to 800ms with wifi power-saving on
(DIR) Post #Ayuc33tmZYVW4g1VrM by amonakov@mastodon.gamedev.place
2025-10-05T21:58:57Z
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@wolf480pl yeah, evidently pinging the access point from the laptop (2-4ms) is not the same as pinging the laptop from the AP (1-200ms) unless I run 'ping -i 0.1 AP' on the laptop (or disable power_save). Which seems to imply the power_save timeout is about 100ms, and I randomly get its extra latency when the response doesn't arrive in that time (e.g. ssh'ing to another continent).
(DIR) Post #AyucO5XBgdFPEDTsgK by wolf480pl@mstdn.io
2025-10-05T22:02:48Z
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@amonakovI should check tomorrow at work if ssh'ing to Japan is faster without wifi power-saving on the client.Anyway, what is certainly faster when I disable power-saving is ssh-ing *to the laptop* (or to the mini-pc)
(DIR) Post #AyvelJWCFqToKGBDdo by Suiseiseki@freesoftwareextremist.com
2025-10-06T10:04:07.137350Z
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@wolf480pl @amonakov Gotta love Wi-Fi cards that run proprietary software eh?
(DIR) Post #Ayvf1jzTbCmL3rhyc4 by wolf480pl@mstdn.io
2025-10-06T10:07:04Z
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@Suiseiseki@amonakov do you think a wifi card that runs free software wouldn't have that feature?do you know of such a card?
(DIR) Post #Ayvfg0B8pbBmqqMXKK by Suiseiseki@freesoftwareextremist.com
2025-10-06T10:14:21.689242Z
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@wolf480pl @amonakov AR9281, AR9382, AR5BXB112 & AR5B22 are all cards that work fine.
(DIR) Post #AyvfqYiPHQOSrOxKyW by Suiseiseki@freesoftwareextremist.com
2025-10-06T10:16:16.372350Z
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@amonakov @wolf480pl None of those cards run any software (all ROM) - the only software is the driver and that's free software.As for usb, AR9271 works fine (free driver and the PCIe to USB bridge software is free).
(DIR) Post #Ayvh95umgQ30zg9DyC by wolf480pl@mstdn.io
2025-10-06T10:30:49Z
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@Suiseiseki@amonakov yeah, okDo these cards not have a power-saving feature?
(DIR) Post #AyvhL0DPhRSKnAXWT2 by wolf480pl@mstdn.io
2025-10-06T10:32:58Z
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@Suiseiseki@amonakov As in, if you let the computer with that card idle, not sending any traffic, and then ping it from the router / access point / another computer on the network, it will still be 2-15ms?
(DIR) Post #AyvipUr2RsC8SXB8JE by Suiseiseki@freesoftwareextremist.com
2025-10-06T10:49:05.943240Z
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@wolf480pl @amonakov The datasheet for a similar card says it has "Dynamic MIMO Power Save"The actual power consumption is not listed, but it seems negligible.If I let the card idle, the ping is still 2-10ms from a GNUbooted router.
(DIR) Post #AyvjKARyMSHO9a4yIq by wolf480pl@mstdn.io
2025-10-06T10:55:13Z
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@Suiseiseki@amonakov > seems negligiblehave you measured it?> similar card says it has Dynamic MIMO Power saveif this one does too, then you should be able to find out how it works by reading the source code, right?
(DIR) Post #AyvlMPUPcFthHiPwGW by Suiseiseki@freesoftwareextremist.com
2025-10-06T11:17:58.584769Z
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@wolf480pl @amonakov >have you measured it?I don't have a mPCIe power measurer, so I can't, but I can see that there's no heatsink.Generally, if something doesn't get hot enough to need a heatsink and if you have 9 18650 cells (rather than a piddly pouch cell), the power consumption of that part isn't much of a concern.>then you should be able to find out how it works by reading the source code, right?Reading drivers/net/wireless/ath/ath9k/main.c there's the ath9k_enable_ps() function to enable powersave. if (!(ah->caps.hw_caps & ATH9K_HW_CAP_AUTOSLEEP)) { if ((ah->imask & ATH9K_INT_TIM_TIMER) == 0) { ah->imask |= ATH9K_INT_TIM_TIMER; ath9k_hw_set_interrupts(ah); } ath9k_hw_setrxabort(ah, 1);It seems that the driver goes and puts the card into powersave mode if packets haven't been transmitted in a timeout period.It looks like it's enabled other than in the case where having powersave enabled uses more power; /* * We just prepare to enable PS. We have to wait until our AP has * ACK'd our null data frame to disable RX otherwise we'll ignore * those ACKs and end up retransmitting the same null data frames. * IEEE80211_CONF_CHANGE_PS is only passed by mac80211 for STA mode. */I'm actually quite pleased with that driver, as it reads like it's actually the source code - don't see magic values and any tables contain what is quite clearly just data.There's the bad Linux habit of almost no comments, but there are at least comments describing things that you can't work out from reading the function like above.
(DIR) Post #AywGBGMyHTWqOR6MLI by loganer@mastodon.social
2025-10-06T17:03:20Z
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@wolf480pl or if you can, don't do it wirelessly.
(DIR) Post #AywKLSPclDKASJSVwe by wolf480pl@mstdn.io
2025-10-06T17:50:03Z
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@loganer yeah