Ryzen 2 and BMI2?

[Gian-Carlo Pascutto]

I agree it is a shame, that Zen is so slow with pext. AMD has to spent some transistors for a fast hardware pext in one cycle!

Note that Intel has several patents on the efficient implementation of those instructions.

[Joost Buijs]

This problem is the reason I'm not going to build 3950x computer on a higher-end B550 board. I'd rather have a 109?0X series Intel (at least the 12 core version) on the old X299 chipset, but the 10X series CPU's are nowhere in sight in the Netherlands, last time I looked. Especially the 10980X.

Last week I could buy a 10980XE-BOX here in the Netherlands (they really exist) but I didn't, 1.5 month ago I shelled out 3.5K for a 3970X machine so I have to wait a little longer otherwise my wife gets angry. The 10940X is readily available now at several online shops.

About half a year ago I already bought all the parts for a 10980XE machine, I got so annoyed by waiting for the 10980XE I bought the 3970X instead.

[mvanthoor]

I see, you're right. The 10940X is available now, for €899.

Now the question becomes: is it still worth it, to put such a CPU on a 3 year old chipset? If Intel doesn't keep the 2066 socket for the successor, The 10X-series is the end of the line for X299. Also, the CPU is quite expensive and "slow" compared to the AMD offerings, except for BMI2 and PEXT. The one thing I REALLY want is a 3950X with a good BMI2 and PEXT implementation.

The next ZEN iteration is planned for this fall. As I don't really NEED a new CPU right now, I should probably just wait and see if AMD fixes BMI2 and PEXT in that iteration, or if Intel introduces something new at the beginning of next year. Rumors of a new Z399 and X599 chipset for the X-cpu's have been circulating for over a year now.

I'm not one to wait for the next "big thing around the corner", except if it's so close (like the new ZEN iteration) that I'd hit my head against a wall repeatedly, if I bought a new computer now and the new ZEN's blow it out of the sky with a new BMI2 and PEXT implementation.

[Joost Buijs]

Now the question becomes: is it still worth it, to put such a CPU on a 3 year old chipset? If Intel doesn't keep the 2066 socket for the successor, The 10X-series is the end of the line for X299. Also, the CPU is quite expensive and "slow" compared to the AMD offerings, except for BMI2 and PEXT. The one thing I REALLY want is a 3950X with a good BMI2 and PEXT implementation.

The next ZEN iteration is planned for this fall. As I don't really NEED a new CPU right now, I should probably just wait and see if AMD fixes BMI2 and PEXT in that iteration, or if Intel introduces something new at the beginning of next year. Rumors of a new Z399 and X599 chipset for the X-cpu's have been circulating for over a year now.

Personally I don't expect that AMD is going to fix BMI2 and PEXT in the next Zen iteration, but maybe I'm wrong. If you don't need a new CPU right now it is certainly better to wait.

As I already have all the parts I'm still going to build the 10980XE machine, I don't care that the chipset is somewhat older, I don't need PCI-E 4.0 for the things I want do with it.

The 3970X is a nice processor, it has some strange quirks too, and what I don't like about it is that it draws a lot of idle current, this is something I don't want for a workstation that runs 14 hours per day.

[Dann Corbit]

The 3970X is a nice processor, it has some strange quirks too, and what I don't like about it is that it draws a lot of idle current, this is something I don't want for a workstation that runs 14 hours per day.

My usage pattern is different.
I run mine pretty close to 24 hours a day and it is almost never idle.
Right now, it has 63 out of 64 threads engaged along with both GPUs.
Of course, I get lots of interesting letters from the power company.

[Joost Buijs]

The 3970X is a nice processor, it has some strange quirks too, and what I don't like about it is that it draws a lot of idle current, this is something I don't want for a workstation that runs 14 hours per day.

My usage pattern is different.
I run mine pretty close to 24 hours a day and it is almost never idle.
Right now, it has 63 out of 64 threads engaged along with both GPUs.
Of course, I get lots of interesting letters from the power company.

This reminds me of the time when it was still profitable to mine bitcoin, I had 2 machine's with 3 of the largest AMD GPU each, 2KW 24/7, the noise and the heat was unbearable.

Sometimes I have jobs that run 24/7 too, for things like developing software, compiling and debugging the 3970X is a bit overkill though.

In the USA power is cheap, here in the Netherlands private homes pay about 25 dollar-cents per KWh.

[jdart]

In the USA power is cheap

It varies by locality. It is not cheap in Northern California. I finally had to get solar because running multiple servers 24/7 was pushing my power bill above $500/month, at least in the summer when I also run air conditioning.

--Jon

[Joost Buijs]

It varies by locality. It is not cheap in Northern California. I finally had to get solar because running multiple servers 24/7 was pushing my power bill above $500/month, at least in the summer when I also run air conditioning.

I've been thinking about solar too, on my roof there is room for 16 panels, I don't know if it is worthwhile with the cloudy weather over here. Last days were quite sunny, but this is more like an exception.

[odomobo]

Does anyone know applications of PDEP and PEXT in a hot loop, outside of computer chess? That should tell us whether AMD will ever prioritize these implementations.

[Dann Corbit]

Crypto and compression:
http://palms.ee.princeton.edu/PALMSopen ... ession.pdf
https://github.com/Forceflow/libmorton/issues/6
https://randombit.net/bitbashing/posts/ ... tions.html