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

Discussion in 'Linux Compatibility and Software' started by Trevayne10, Jan 27, 2020.

  1. Trevayne10

    Trevayne10 Notebook Consultant

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    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)
     
    Last edited: Jan 27, 2020
  2. Vasudev

    Vasudev Notebook Nobel Laureate

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    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.
     
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  3. Trevayne10

    Trevayne10 Notebook Consultant

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    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
     
  4. Vasudev

    Vasudev Notebook Nobel Laureate

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    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.
     
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