NVIDIA Proposes The Linux Hardware Timestamping Engine

[phoronix]

Phoronix: NVIDIA Proposes The Linux Hardware Timestamping Engine

A proposal by NVIDIA engineers for the mainline Linux kernel would introduce the Hardware Timestamping Engine (HTE) subsystem...

https://www.phoronix.com/scan.php?page=news_item&px=Linux-Hardware-Timestamp

[Adarion]

But does this hardware time-stamps-providing enginge work correctly and reliably? I remember HPET was supposed to provide something similar, but a lot of these HPETs were quite "special" in handling.

[Azrael5]

Which cards will benefit from this feature?

[stormcrow]

Which cards will benefit from this feature?

GPU cards? None? Did you read the article?

[Zan Lynx]

This kind of thing is especially useful on mobile and embedded hardware where the CPU is often idle and shutdown with no interrupts, and the CPU cores also speed scale.

On x86 Linux systems it can be quite an effort to get an accurate timestamp, especially if the OS is waking up a thread on a different core, and with things like queued PCIe interrupts. MSI, I think those are called. There can be quite a delay (in interrupt terms) between a device sending MSI and the CPU getting it handled. Well, that is also true of regular interrupts, because the handler has to loop to handle every device that might have raised a shared interrupt.

I believe I remember reading that some of the flicker bugs in Nvidia's old SLI system were because of inaccurate time stamping.

[timofonic]

IIs it just me or is this just a disguised plan for stronger DRM?

[coder]

Nice feature!

I'm curious if they provide any support for mapping between the timestamp domains of different providers. Besides the mere ability to generate high-precision timestamps, that's the other thing I'd really like to see.

[Azrael5]

GPU cards? None? Did you read the article?

I need the list.

[jabl]

IIs it just me or is this just a disguised plan for stronger DRM?

It's just you.

[MuPuF]

GPU cards? None? Did you read the article?

Nvidia's timer block has been roughly the same since the TNT2. All their cards have a 32ns resolution for their time IIRC.