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Comment by fnordpiglet | Hacker News Reader

It’s a lot more nuanced than that. Being in a data center doesn’t imply heavy network utilization. The caveat is clearly outlined in the article being workload based not deployment based. If you have a home machine doing network routing it would absolutely benefit from this. In fact I would say probably the vast majority of Linux installs are home network devices, just people don’t know it. Embedded Linux machines doing network routing or switching or IPS or NAS or whatever would benefit a lot from this. “Energy savings” can be seen as a green washing statement but on embedded budgets it’s a primary requirement.

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> If you have a home machine doing network routing it would absolutely benefit from this.

It most likely won't. This patch set only affects applications that enable epoll busy poll using the EPIOCSPARAMS ioctl. It's a very specialized option that's not commonly used by applications. Furthermore, network routing in Linux happens in the kernel, not in user space, so this patch set doesn't apply to it at all.

NAPI is not busy poll, though, and the way the article is worded suggests it's about NAPI.

Now, NAPI already was supposed to have some adaptiveness involved, so I guess it's possibly a matter of optimizing it.

But my system is compiling for now so will look at article more in depth later :V

The article is terrible, this doesn't affect the default NAPI behaviour. See the LWN link posted elsewhere for a more detailed, technical discussion. From the patch set itself:

> If this [new] parameter is set to a non-zero value and a user application has enabled preferred busy poll on a busy poll context (via the EPIOCSPARAMS ioctl introduced in commit 18e2bf0edf4d ("eventpoll: Add epoll ioctl for epoll_params")), then application calls to epoll_wait for that context will cause device IRQs and softirq processing to be suspended as long as epoll_wait successfully retrieves data from the NAPI. Each time data is retrieved, the irq_suspend_timeout is deferred.

> I would say probably the vast majority of Linux installs are home network devices

I'm expect there are many, but the vast majority are likely massive datacenters with hundreds of thousands of machines each running multiple instances, and also Android phones are probably more common than home equipment. Edit: Also IoT, as someone else points out.

The vast majority of Linux kernels run on Android.

I would be shocked if I am incorrect.

I could see that being right. At the same time, how many servers running Linux are there, and how many instances per server?

> It’s a lot more nuanced than that. Being in a data center doesn’t imply heavy network utilization.

I suggest you reread “software used in datacenters (e.g. by CDNs) that does use it”. This is not a reference to software in a datacenter. It is a reference to software in a datacenter that uses it, which is a subset of the former.

I was curious how much this would be applicable to home routers.

I confess I'm dubious on major savings for most home users, though? At least, at an absolute level. 30% of less than five percent is still not that big of a deal. No reason not to do it, but don't expect to really see the results there.

For embedded it’s not about saving cost it’s about saving limited on board power. The lower the power demand of the device, the smaller and the more you can dedicate to other things.

Again, no reason not to do this change. I'm not clear it helps in this case, though? The savings is in low use time. During high use time, it is the same, right?

Practically none of it would be applicable (if using a commercial router). They all use hardware offloading, and traffic seldom touches the CPU. Only "logical" tasks are raised to the CPU, like ARP resolution and the likes (what’s called "trap to cpu").

If you’re doing custom routing with a NUC or a basic Linux box, however, this would gain massive power savings because that box pretty much only does networking.

Only if you're using busy polling. Very little software uses it, because it's only a good fit if you think pegging a CPU to reduce latency responding to packets is a good trade.

Yup, you’re right. I always forget this patch only applies to opted-in polling and not automatic polling for interrupt moderation.

if you run a VPN server, i assume all the traffic will come to CPU to decrypt, right?

There should have been an off switch from the beginning though IMO, though perhaps there already is? But the number of corporates messing with the kernel for their own purposes greatly outnumbers the number of independent developers. That gives big tech a big influence. And the Linux Foundation is there to cement that influence.

I much prefer grassroots projects. Made by and for people like me <3 That's why I moved to BSD (well there were other reasons too of course)

Uh Linux is a grassroots project, quite unlike Berkley Software Distribution.

Also no you are entirely unaffected by this unless you use a very specific and uncommon syscall.

It was originally, yes. There's a lot of corporate influence now (just look at the monthly kernel submissions). https://news.itsfoss.com/huawei-kernel-contribution/

Like others have mentioned, it's just a huge deal in the data center now. With that comes a lot of influence by corporates interests.

Whereas BSD has gone the opposite way. Started by Berkeley but abandoned to the community. Business is not really interested in that because anything they contribute can be used by anyone for anything (even their competitors can use it in closed source code). Netflix was the biggest user but I don't think they contribute anymore either. WhatsApp used it until Facebook acquired them. That leaves netgate and ix systems which are small. Netgate pushed a really terrible wireguard once but it was nipped in the bud luckily. https://arstechnica.com/gadgets/2021/03/buffer-overruns-lice... It also highlighted many trust issues which have been improved since.

Of course whether this is an issue for you is very personal. For me it is but clearly for a lot more people it isn't, as Linux is s lot more popular.

No it's not an issue to me, just pointed out a factual mistake.

Linux has been a corporate project for at least 20 years.

That roots part in grassroots means something.

Yes, but I don't think it means what you think it means? Just because Linux was developed by basement dwelling hackers 20+ years ago, doesn't make it a grassroots project.

Arguably, the only somewhat mainstream operating systems today that deserve that label are the *BSDs. Haiku OS gets an honorable mention but I wouldn't consider Haiku OS to be mainstream.

It quite literally makes it a grassroots project.

> Arguably, the only somewhat mainstream operating systems today that deserve that label are the *BSDs.

I think the word you're looking for is 'sidelined'.

Meh not really. I'm running BSD with the very latest software. KDE, Firefox, Chrome, LibreOffice. All rolling unlike most Linux distros. I really don't care how 'big' my OS is.

But yeah grassroots was perhaps not the right term. I meant the status quo, not the origin. I don't know what the right word is then though.

What home router would be busy polling?

Someone who decided to turn their old PC into a router because a youtube video daid "recycling" an old PC is more green despite the massive power suck.

I feel like I'm repeating myself, but there are no people out there running Linux and unintentionally busy polling their network interface. This is something almost nobody does.

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