7 ms·

Show HN: Terminal dashboard that throttles my PC during peak electricity rates

98 points by naveen_k 2y ago

WattWise is a CLI tool that monitors my workstation’s power draw using a smart plug and automatically throttles the CPU & GPUs during expensive Time-of-Use electricity periods. Built with Python, uses PID controllers for smooth transitions between power states. Works with TP-Link Kasa plugs and Home Assistant.

ajsnigrutin 2y ago
Why all this instead of a simple cronjob switching from performance to powersave profiles depeding on current time (=electricity price)?
- pests 2y ago
  I'm on a time of use rate plan, most expensive from 11am-7pm. However they also have "Critical Peak Events" which increase the rate about 10x to over a $1/kwh that last up to 4 hours. Just saying it would be a bit more complex then just checking the time.
  - ajsnigrutin 2y ago
    So how do you get that data (status) now (if(is-critical-peak-event){})? Do the smartplugs gather some smartgrid-style data?
    - pests 2y ago
      I do believe I've seen some plugs that do connect to some data source to do it automatically, but I'd rather not give plugs access to the internet haha. Our provider also gives advanced notice via text or email so its totally possible to connect it up yourself.
    - joshvm 2y ago
      It depends on your supplier, because they set the pricing and that information gets displayed on your meter. Octopus (UK) has a dynamically-priced service called Agile where you can query the API as a user; in some cases the API doesn't even need a login for regional pricing. You would have to build some logic on top for most smartplugs through something like HomeAssistant. There are storage batteries which can react to pricing, and some which will also work in concert with current solar power or other renewables. https://octopus.energy/blog/agile-smart-home-diy/ https://octopus.energy/blog/agile-smart-home-diy/ https://www.zerofy.net/2024/03/26/meter-data.html https://www.zerofy.net/2024/03/26/meter-data.html for some more European info on meters, though mostly focused on accessing your own usage data.
- naveen_k 2y ago
  A cronjob would definitely work in most cases if the goal is just to auto change freq profiles during set ToU periods. I just wanted a more flexible system where the system can auto change the profiles based on actual utilization so demanding tasks aren't slowed down.
throwaway3231 2y ago
It's usually more energy-efficient to finish a task quickly with a higher power draw, also known as race-to-idle.
- naveen_k 2y ago
  Good point. I'm often running multiple parallel jobs with varying priorities where uniform throttling actually makes sense. Many LLM inference tasks are long-running but not fully utilizing hardware (often waiting on I/O or running at partial capacity) The dual Epyc CPUs (128 cores) in my setup have a relatively high idle power draw compared to consumer chips. Even when "idle" they're consuming significant power maintaining all those cores and I/O capabilities. By implementing uniform throttling when utilization is low, the automation actually reduces the baseline power consumption by a decent amount without much performance hit.
  - foobarian 2y ago
    It seems it may be relatively accessible to take a few representative tasks and actually measure the soup-to-nuts energy consumed at the plug. Would be very interesting to see in tandem with the power optimizations!
    - naveen_k 2y ago
      That's exactly what I did first! I ran a CPU torture test at full clock speed and measured the power draw at the plug, then repeated the same test with the lowest clock speed setting. For the Epyc system, there was about 225W lower power draw at the reduced clock speed. Even at idle, capping the max frequency reduced the power draw by about 20+%.
PeterStuer 2y ago
Nice project, but would it not be more rational to have your system running underclocked/undervolted at the optimal perf/watt at all times, with an optional boost to max performance for a time critical task? Running it away from the optimum might save on instant consumption but increase your aggregate consumption.
- throwaway3231 2y ago
  It's well established that completing the same task more slowly at a lower clock rate is actually less energy-efficient.
  - yjftsjthsd-h 2y ago
    Right, "race to idle"
- nottorp 2y ago
  How is it with modern overclocked by default cpus? If you cut power use by 50% you still get 80% of the performance?
- blitzar 2y ago
  Bring back the "turbo" button on the front of the PC.
- naveen_k 2y ago
  Thanks! That's an excellent point. You're right that there's likely a sweet spot that would be more efficient overall than aggressive throttling. The current implementation uniformly sets max frequency for all 128 cores, but I'm working on per-core frequency control that would allow much more granular optimization. I'll definitely measure aggregate consumption with your suggestion versus my current implementation to see the difference.
  - csdvrx 2y ago
    Another suggestion: when you want to save power, use irq affinity with /proc/irq/$irq/smp_affinity_list to put them all on one core. This core will get to sleep less than the others. You can also use the CPU "geometry" (which cores share cache) to set max frequency on its neighboring cores first, before recruiting the other cores
gtirloni 2y ago
Could you share how much you have saved in $?
- naveen_k 2y ago
  The power optimizer daemon has only been running for a few days, so it's hard to measure in $ value but based on my peak pricing I would estimate the savings to be around a few dollars since then.
whalesalad 2y ago
Wonder if a big UPS/power bank would be better? Charge it during periods where power is cheaper, and utilize it when power is more expensive. Then again if you do not need full performance all the time - this is a cool solution.
- naveen_k 2y ago
  Definitely, I've been contemplating getting a 5-10kWh LFP battery backup with <10ms UPS switchover to run the workstation and home backup. This is an intermediate solution until then.
russdill 2y ago
If your computer is still doing bursty jobs during that period, it will use less power but still as much energy. Sure, you can reduce the power but if you aren't also reducing what you ask it to do, it'll just use that max amount of allowed power for a longer period of time.
- PaulKeeble 2y ago
  All the modern CPUs will boost into high clockspeeds and voltage to get work done quicker but at considerably higher power draws per operation. On that side of the equation its clear that it uses more energy. The problem is the entire CPU package is on longer if you don't do that and this costs power too and so its a trade off between the two. Generally we consider there isn't much difference between them but I don't know about that having seen the insanity that was the 13th and 14th gen Intel's consuming 250W when 120W gets about 95% the performance I think its very likely moving down to power save and avoiding that level of boosting definitely saves small amounts of power.
  - delusional 2y ago
    This is some pretty old analysis, but I remember when smartphones came out and people were thinking about throttling their applications to lower power consumption the general advice was to just "race to idle". The consensus thus was that spending more time in lower power states (where you use ~0W) was much more efficient than spending a longer amount of time in the CPU sweetspot, but with all sort of peripherals online that you didn't need anyway. I remember when Google made a big deal out of "bundling" idle CPU and network requests, since bursting them out was more efficient than having the radio and CPU trotting along at low bandwidth.
    - wongarsu 2y ago
      However there are two factors that might make "race to idle" more valid on phones than on most other platforms: Smartphone chips are designed to much stricter thermal and power limits. There is only so much power you can get out of the tiny battery, and only so much heat you can get rid of without making the phone uncomfortably hot. Even in a burst that puts a limit on the wastefulness. Desktop CPUs are very different: If you can get 10% more performance while doubling power draw, people will just buy bigger coolers and bigger power supplies to go along with the CPU. Notebook CPUs are somewhere in the middle: limited, but with much better cooling and much more powerful batteries than phones. The other thing is the operating system: "race to idle" makes sense in phones because the OS will actually put the CPU into sleep states if there's nothing to do, and puts active effort into not waking the CPU up unnecessarily and cramming work into the time slots when the CPU is active anyways. Desktop operating systems just don't do that to the same degree. You might race to idle, but the rest of the system will then just waste power with background work once it's idle.
PeterStuer 2y ago
Had a quick look through the code but I can't find where he actually throttles the PC. Anyone can point me to it? https://github.com/naveenkul/WattWise https://github.com/naveenkul/WattWise
- dartos 2y ago
  Yeah I don’t see anything that even suggests it throttles the PC. Looks like it’s just a display.
  - dylan604 2y ago
    You mean like the title of the submission suggestion of it throttling?
    - dartos 2y ago
      I meant in the code……… obviously…
- naveen_k 2y ago
  Sorry, I only open sourced the dashboard part as mentioned in the bottom of the blogpost. Still working on improving the 'Power optimizer' service so will open source that soon as well.
  - PeterStuer 2y ago
    If it were up to me I would go for switching complete performance profiles through something like tuned-adm rather than trying to change just cpu frequencies. There's too many interlinked things that can have an effect on throughput efficiency.
    - naveen_k 2y ago
      Thanks, I'll check it out.
Havoc 2y ago
From what I’ve seen price per token make home generation uncompetitive in most countries. And that’s just on elec - never mind cost of gear Only really makes sense for learning or super confidential info
naveen_k 2y ago
Quick update: Definitely wasn't expecting this to end up on the front page. I was more focused on publishing the dashboard than the power optimizer service I'm running. I'll take all the feedback into account and will open source an improved version of it soon. Appreciate all the comments!
- vondur 2y ago
  That's quite a beefy workstation you got there!
gitpusher 2y ago
People have made valid criticisms about the basic effectiveness of your strategy. But in any case, this is a pretty awesome hacker project - nicely done! Love the appearance of your CLI tool. I am definitely bookmarking for future inspo
- naveen_k 2y ago
  Thanks! I initially just wanted to build a dashboard, with the power optimization part being a later addition. Based on the HN response, it seems that's the feature that resonated most with people. I'll be making improvements to the optimization component in the coming days and will publish what I have.
gorbypark 2y ago
Pretty neat! I’m currently working on a project that uses an ESP-C6 that just exposes a “switch” over matter/thread thats based off the results from the Spanish electricity prices API. The idea is have the switch be on when it’s one of the cheapest hours of the day, and off otherwise. Then other automations can be based on it. This was pretty trivial to do in home assistant but I want something that’s ultra low power and can just be completely independent of anything for less technical users. My end goal is to have a small battery powered device that wakes up from deep sleep once a day to check the day ahead prices via WiFi. The C6 might be overkill for this, but once I have a proof of concept working I’ll try and pick something that’s ultra low super ultra low power. Something that needs charging once or twice a year would be ideal. The ideal form factor might be a smart plug itself, but I can’t find any with hackable firmware and also matter/thread/wifi.
- naveen_k 2y ago
  That's actually pretty cool. ESPs are awesome little things.
black_13 2y ago
[dead]
Symbiote 2y ago
Within the next year or two, I'm going to look at implementing something similar at my work. We don't pay for electricity directly (it's included in the rackspace rental), but we could reduce our carbon footprint by adjusting the timing of batch processing, perhaps based on the carbon intensity APIs from https://app.electricitymaps.com/ https://app.electricitymaps.com/ Though, the first step will be to quantify the savings. I have the impression from being in the datacentre while batch jobs have started that they cause a significant increase in power use, but no numbers.
- dehrmann 2y ago
  Can you run the batch processing on other machines at off-peak hours?
- reaperman 2y ago
  You’re probably already on top of it but if your company doesn't operate the datacenter you’ll also want to estimate the carbon cost of cooling in addition to the electricity that the machines consume.
mythrwy 2y ago
This looks cool but I feel it should notify the user with a snip from the song "You Suffer" by "Napalm Death" when throttling occurs.

98 points by naveen_k 2y ago

ajsnigrutin 2y ago

Why all this instead of a simple cronjob switching from performance to powersave profiles depeding on current time (=electricity price)?

pests 2y ago
I'm on a time of use rate plan, most expensive from 11am-7pm. However they also have "Critical Peak Events" which increase the rate about 10x to over a $1/kwh that last up to 4 hours. Just saying it would be a bit more complex then just checking the time.
- ajsnigrutin 2y ago
  So how do you get that data (status) now (if(is-critical-peak-event){})? Do the smartplugs gather some smartgrid-style data?
  - pests 2y ago
    I do believe I've seen some plugs that do connect to some data source to do it automatically, but I'd rather not give plugs access to the internet haha. Our provider also gives advanced notice via text or email so its totally possible to connect it up yourself.
  - joshvm 2y ago
    It depends on your supplier, because they set the pricing and that information gets displayed on your meter. Octopus (UK) has a dynamically-priced service called Agile where you can query the API as a user; in some cases the API doesn't even need a login for regional pricing. You would have to build some logic on top for most smartplugs through something like HomeAssistant. There are storage batteries which can react to pricing, and some which will also work in concert with current solar power or other renewables. https://octopus.energy/blog/agile-smart-home-diy/ https://octopus.energy/blog/agile-smart-home-diy/ https://www.zerofy.net/2024/03/26/meter-data.html https://www.zerofy.net/2024/03/26/meter-data.html for some more European info on meters, though mostly focused on accessing your own usage data.
naveen_k 2y ago
A cronjob would definitely work in most cases if the goal is just to auto change freq profiles during set ToU periods. I just wanted a more flexible system where the system can auto change the profiles based on actual utilization so demanding tasks aren't slowed down.

throwaway3231 2y ago

It's usually more energy-efficient to finish a task quickly with a higher power draw, also known as race-to-idle.

naveen_k 2y ago
Good point. I'm often running multiple parallel jobs with varying priorities where uniform throttling actually makes sense. Many LLM inference tasks are long-running but not fully utilizing hardware (often waiting on I/O or running at partial capacity) The dual Epyc CPUs (128 cores) in my setup have a relatively high idle power draw compared to consumer chips. Even when "idle" they're consuming significant power maintaining all those cores and I/O capabilities. By implementing uniform throttling when utilization is low, the automation actually reduces the baseline power consumption by a decent amount without much performance hit.
- foobarian 2y ago
  It seems it may be relatively accessible to take a few representative tasks and actually measure the soup-to-nuts energy consumed at the plug. Would be very interesting to see in tandem with the power optimizations!
  - naveen_k 2y ago
    That's exactly what I did first! I ran a CPU torture test at full clock speed and measured the power draw at the plug, then repeated the same test with the lowest clock speed setting. For the Epyc system, there was about 225W lower power draw at the reduced clock speed. Even at idle, capping the max frequency reduced the power draw by about 20+%.

PeterStuer 2y ago

Nice project, but would it not be more rational to have your system running underclocked/undervolted at the optimal perf/watt at all times, with an optional boost to max performance for a time critical task? Running it away from the optimum might save on instant consumption but increase your aggregate consumption.

throwaway3231 2y ago
It's well established that completing the same task more slowly at a lower clock rate is actually less energy-efficient.
- yjftsjthsd-h 2y ago
  Right, "race to idle"
nottorp 2y ago
How is it with modern overclocked by default cpus? If you cut power use by 50% you still get 80% of the performance?
blitzar 2y ago
Bring back the "turbo" button on the front of the PC.
naveen_k 2y ago
Thanks! That's an excellent point. You're right that there's likely a sweet spot that would be more efficient overall than aggressive throttling. The current implementation uniformly sets max frequency for all 128 cores, but I'm working on per-core frequency control that would allow much more granular optimization. I'll definitely measure aggregate consumption with your suggestion versus my current implementation to see the difference.
- csdvrx 2y ago
  Another suggestion: when you want to save power, use irq affinity with /proc/irq/$irq/smp_affinity_list to put them all on one core. This core will get to sleep less than the others. You can also use the CPU "geometry" (which cores share cache) to set max frequency on its neighboring cores first, before recruiting the other cores

gtirloni 2y ago

Could you share how much you have saved in $?

naveen_k 2y ago
The power optimizer daemon has only been running for a few days, so it's hard to measure in $ value but based on my peak pricing I would estimate the savings to be around a few dollars since then.

whalesalad 2y ago

Wonder if a big UPS/power bank would be better? Charge it during periods where power is cheaper, and utilize it when power is more expensive. Then again if you do not need full performance all the time - this is a cool solution.

naveen_k 2y ago
Definitely, I've been contemplating getting a 5-10kWh LFP battery backup with <10ms UPS switchover to run the workstation and home backup. This is an intermediate solution until then.

russdill 2y ago

If your computer is still doing bursty jobs during that period, it will use less power but still as much energy. Sure, you can reduce the power but if you aren't also reducing what you ask it to do, it'll just use that max amount of allowed power for a longer period of time.

PaulKeeble 2y ago
All the modern CPUs will boost into high clockspeeds and voltage to get work done quicker but at considerably higher power draws per operation. On that side of the equation its clear that it uses more energy. The problem is the entire CPU package is on longer if you don't do that and this costs power too and so its a trade off between the two. Generally we consider there isn't much difference between them but I don't know about that having seen the insanity that was the 13th and 14th gen Intel's consuming 250W when 120W gets about 95% the performance I think its very likely moving down to power save and avoiding that level of boosting definitely saves small amounts of power.
- delusional 2y ago
  This is some pretty old analysis, but I remember when smartphones came out and people were thinking about throttling their applications to lower power consumption the general advice was to just "race to idle". The consensus thus was that spending more time in lower power states (where you use ~0W) was much more efficient than spending a longer amount of time in the CPU sweetspot, but with all sort of peripherals online that you didn't need anyway. I remember when Google made a big deal out of "bundling" idle CPU and network requests, since bursting them out was more efficient than having the radio and CPU trotting along at low bandwidth.
  - wongarsu 2y ago
    However there are two factors that might make "race to idle" more valid on phones than on most other platforms: Smartphone chips are designed to much stricter thermal and power limits. There is only so much power you can get out of the tiny battery, and only so much heat you can get rid of without making the phone uncomfortably hot. Even in a burst that puts a limit on the wastefulness. Desktop CPUs are very different: If you can get 10% more performance while doubling power draw, people will just buy bigger coolers and bigger power supplies to go along with the CPU. Notebook CPUs are somewhere in the middle: limited, but with much better cooling and much more powerful batteries than phones. The other thing is the operating system: "race to idle" makes sense in phones because the OS will actually put the CPU into sleep states if there's nothing to do, and puts active effort into not waking the CPU up unnecessarily and cramming work into the time slots when the CPU is active anyways. Desktop operating systems just don't do that to the same degree. You might race to idle, but the rest of the system will then just waste power with background work once it's idle.

PeterStuer 2y ago

Had a quick look through the code but I can't find where he actually throttles the PC. Anyone can point me to it? https://github.com/naveenkul/WattWise https://github.com/naveenkul/WattWise

dartos 2y ago
Yeah I don’t see anything that even suggests it throttles the PC. Looks like it’s just a display.
- dylan604 2y ago
  You mean like the title of the submission suggestion of it throttling?
  - dartos 2y ago
    I meant in the code……… obviously…
naveen_k 2y ago
Sorry, I only open sourced the dashboard part as mentioned in the bottom of the blogpost. Still working on improving the 'Power optimizer' service so will open source that soon as well.
- PeterStuer 2y ago
  If it were up to me I would go for switching complete performance profiles through something like tuned-adm rather than trying to change just cpu frequencies. There's too many interlinked things that can have an effect on throughput efficiency.
  - naveen_k 2y ago
    Thanks, I'll check it out.

Havoc 2y ago

From what I’ve seen price per token make home generation uncompetitive in most countries. And that’s just on elec - never mind cost of gear Only really makes sense for learning or super confidential info

naveen_k 2y ago

Quick update: Definitely wasn't expecting this to end up on the front page. I was more focused on publishing the dashboard than the power optimizer service I'm running. I'll take all the feedback into account and will open source an improved version of it soon. Appreciate all the comments!

vondur 2y ago
That's quite a beefy workstation you got there!

gitpusher 2y ago

People have made valid criticisms about the basic effectiveness of your strategy. But in any case, this is a pretty awesome hacker project - nicely done! Love the appearance of your CLI tool. I am definitely bookmarking for future inspo

naveen_k 2y ago
Thanks! I initially just wanted to build a dashboard, with the power optimization part being a later addition. Based on the HN response, it seems that's the feature that resonated most with people. I'll be making improvements to the optimization component in the coming days and will publish what I have.

gorbypark 2y ago

Pretty neat! I’m currently working on a project that uses an ESP-C6 that just exposes a “switch” over matter/thread thats based off the results from the Spanish electricity prices API. The idea is have the switch be on when it’s one of the cheapest hours of the day, and off otherwise. Then other automations can be based on it. This was pretty trivial to do in home assistant but I want something that’s ultra low power and can just be completely independent of anything for less technical users. My end goal is to have a small battery powered device that wakes up from deep sleep once a day to check the day ahead prices via WiFi. The C6 might be overkill for this, but once I have a proof of concept working I’ll try and pick something that’s ultra low super ultra low power. Something that needs charging once or twice a year would be ideal. The ideal form factor might be a smart plug itself, but I can’t find any with hackable firmware and also matter/thread/wifi.

naveen_k 2y ago
That's actually pretty cool. ESPs are awesome little things.

black_13 2y ago

[dead]

Symbiote 2y ago

Within the next year or two, I'm going to look at implementing something similar at my work. We don't pay for electricity directly (it's included in the rackspace rental), but we could reduce our carbon footprint by adjusting the timing of batch processing, perhaps based on the carbon intensity APIs from https://app.electricitymaps.com/ https://app.electricitymaps.com/ Though, the first step will be to quantify the savings. I have the impression from being in the datacentre while batch jobs have started that they cause a significant increase in power use, but no numbers.

dehrmann 2y ago
Can you run the batch processing on other machines at off-peak hours?
reaperman 2y ago
You’re probably already on top of it but if your company doesn't operate the datacenter you’ll also want to estimate the carbon cost of cooling in addition to the electricity that the machines consume.

mythrwy 2y ago

This looks cool but I feel it should notify the user with a snip from the song "You Suffer" by "Napalm Death" when throttling occurs.