2x xeon 5670 seems slow

[benmcgr]

Hi,

I just got a new machine to create DCPs. I'm getting about 9.5-10 fps 2k encoding. Was hoping for better speed. Does this seem correct? Here are the specifications:

hp Z600
2x Intel Xeon 5670 2.93GHz
24GB RAM
500 GB ssd - 400 GB free
Nvidia Quadro 600

64 bit Windows 10 Pro

DCP-o-matic defaulted to 12 threads correctly.

I'm testing on the machine using Batch Converter and not using it as a server to avoid any network issues. All work is on the ssd.

Thank you for your input!

[Carsten]

This is a dual CPU 6core + HT machine, so 2*6*2 =24 is the proper thread setting - start up task manager and you should see 24 CPU performance scales, one for every logical core. You may need to right-click on the CPU graph in order to switch to per-core display.

https://youtu.be/oilyee1UUyM?t=213

Note that some mainboard bios or windows startup settings allow to disable HyperThreading, so if you don't see 24, but only 12 cores, you should check these settings. Since DCP-o-matic defaulted to 12 threads, it either chose the wrong setting, misdetected the CPU config, or some of these HT disable settings is active. Also possible that 12 threads had been stored in prefs from a previous installation/system. The CPU autodetect is only performed once during initial installation and setup.

As a matter of fact, I often see some (small) performance improvement when setting slightly more than 24 compute threads, like 30-36 or so. This is no problem even on a machine with less logical cores. You just need enough memory (24GB is perfectly okay, even for 4k) - and overdoing it gives no benefit.

[IoannisSyrogiannis]

I once read that HyperThreading is not a great benefit, and not x2 in any way, to the computing power of CPUs.
Does experience suggest otherwise?

[Carsten]

At least with DOM's J2K, it actually nearly doubles the performance. I just looked it up - the Z600 BIOS does indeed allow to deactivate HT in BIOS-Processor settings. So that would be the first place to look at.

I noticed, however, when I bought my second 'second hand' Z600 Xeon 5675 machine (nearly 10 years old at the time), and downloaded drivers for the OS installation, that there was a very current BIOS update available for it. I was pleased at first and installed it, and performance dropped considerably compared to my first machine. I looked up the Readme, and it actually was a security update BIOS dealing with the SPECTRE virus, applying some changes to the CPU microcode.
So, I traded in performance for security. Luckily, I found a way to downgrade to the latest pre-SPECTRE BIOS. I don't feel unsafe, because this machine is only used for some specific applications and usually not connected to the internet. Most of the time, it is just a DCP-o-matic encoding server.

[IoannisSyrogiannis]

With a Z840, checking with Sintel, I first got 28fps.
Then, I combined it with a Z600 and got up to 37fps.
I sent the logs to Carl some time ago.

Today, I enabled HyperThreading and used 55 out of 56 (threads again) to get from 28 to 31 fps.
I am not trying to say that the difference between using HyperThreading and not is 3 fps.
There are so many factors also taking part in all this. I saw the fps hiking up to 39fps at some point and dropping to 22 at another. Also, even with 200Mbps, it is a scope DCP that is made. Flat would make a difference.
Its BIOS is M60 v02.57. I haven't had a look on what that may mean.
Also, when I first took the test, a couple of programs (and services) were not installed.

Yet, those tests made me wonder if there is merit to (all) different opinions regarding the impact of HyperThreading on demanding CPU tasks.

[Carsten]

It certainly depends on processor type and possibly also the spectre patch status, as the spectre vulnerability as far as I know is based on HT and multithreading.


- Carsten