changing power plan drastically reduces download speed

[jagannatharjun]

Please provide the following information

libtorrent version (or branch):
libtorrent v1.2.19.0

platform/architecture:
windows 11

compiler and compiler version:
msvc

please describe what symptom you see, what you would expect to see instead and
how to reproduce it.

when I change my power plan from "High Performance" to "Power Saver", the download speed drastically decrease, changing the power plan back to "High Performance" again increases download speed, weirdly doesn't seem to affect upload speed

In above image, the red circle is the download speed in "Power Saver" mode

[vincejv]

I'm not entirely sure where you're getting at... or your expectations? You expect the speeds to be the same when your CPU is throttled down by the power plan due to power saving?

Downloading requires CPU time due to piece hash checking by throttling down your CPU thru switching power plans will obviously lower your download speed.

Not to mention that probably your Network drivers/card requiring CPU time not being hardware accelerated or no dedicated chip in the PCIe card to process packets.

[jagannatharjun]

throttling down your CPU

I tried changing "maximum processort state" in power plan setting for both of these power plan, the result remains same, so it's something else.

[vincejv]

You're going to have list all the change between power plans for someone to help

How are others suppose to know what you set?? i mean I even assumed your CPU is throttled down with your "Power Saving" plan.

[arvidn]

It's not obvious that there's anything wrong here. Downloading at a lower rate will most likely save power; so it seems to work as intended.

If you have a reason to believe there's something wrong, and the download rate should not be affected by the computation power afforded by the hardware, please describe the reasons to believe so.

[jagannatharjun]

the download rate should not be affected by the computation power afforded by the hardware, please describe the reasons to believe so

because upload rate is not being affected

[elgatito]

@jagannatharjun When you download - all downloaded blocks are being hashed and verified, that uses CPU for hashing and IO for writing/downloading.

When you upload - you use downloaded data 'as is', so you use only IO for read/upload.

I don't think power plan would influence networking layer, but hashing would be done slower, definitely, so it should influence your download performance, yes.