Ubuntu 18.04 - Hyper Threading, or more GHz? (WCG / BOINC)

I have a Toshiba Satellite L755 15.6" laptop (35W TDP), which is running a 45W intel core i7-2760QM CPU (4 physical/4 logical cores - 8 threads total, @2.4 - 3.5 GHz). Ubuntu Linux 18.04. 8 GB DDR3-1600 CL11 (PC3-12800), PNY 256GB SSD

The CPU throttles quite a bit and doesn't Turbo to 3.2 / 3.3 / 3.5 GHz very well - laptop is 35W TDP, wasn't designed for 45W CPU - lesson learned - but does have good quality 130W power brick. I also installed a NOS Toshiba CPU fan 4 months ago, and gave the CPU & heat sink a good Arctic Silver 5 pasting (using the thin line application, running right to the edges of the CPU die).

The laptop runs World Community Grid / BOINC 64-bit work loads (Mapping gene cancer markers) just fine under full load (100%), 24/7/365 at the base speed of 2.4 GHz with all 4 cores /8 threads. The CPU temps never exceed 82°C on any of the cores, or on the CPU package. Locked in on rails at 2.4 GHz.

I've discovered that under Linux I can disable Hyper Threading on the CPU, and the CPU increases its base clock speed to 2.6 GHz on the 4 physical cores. I did some benchmarking, but the before/after results are very inconclusive.

My question is: for most applications, which scenario would likely yield greater workload results:

2.4 GHz max CPU clock speed on all 4 cores, with Hyper threading enabled (4C/8T)

- or -

2.6 GHz max CPU clock speed on all 4 cores, with Hyper Threading disabled (4C/4T) ?

Thanks in advance,

- Trev


btw, in case anyone is interested, this laptop generates WCG/BOINC workload results that are about 30% greater (over same period of time) under Ubuntu Linux x64 than under Windows 10 Pro x64. It also usually beats my Asus 17" laptop with a Haswell i7-4700HQ quad core CPU by about 4%, running the same WCG/BOINC 100% gene marker workloads under Windows 10 Pro x64 (all else being equal: locked in at 2.4 GHz, HTT enabled, Turbo disabled)

 

I think you can use TLP and tuned-gtk/tuned cmd line utils to optimize CPU thermals. BTW, change your paste from AS5 to ICD 7 or better to reduce those temps to 75C.
You can disable Turbo in TLP in both battery and AC.

 

Thanks, Vasudev. Unfortunately with Sandy Bridge, intel gutted CPU thermal and frequency control (for the most part), even in Linux.
I'll look into Icy Diamond 7 thermal paste.



But which configuration do you think will produce greater workload results?


2.4 GHz max CPU clock speed on all 4 cores, with Hyper threading enabled (4C/8T)

- or -

2.6 GHz max CPU clock speed on all 4 cores, with Hyper Threading *DISABLED* (4C/4T) ?

in other words, 8 threads at 2.4 GHz, or 4 (real) threads at 2.6 GHz?

Thanks again,

- Trev

 

Depends on clock speeds that work at all core active. If its higher you get better performance otherwise you don't see major improvements.
I believe you should stick with HT disabled since you get see almost same performance with extra virtual cores with lower boost clocks.