The docs could be improved to mention pmtools package, which includes turbostat utility. It can be used by users to inspect at what frequency their CPU and cores run at the moment, and decode whether to enable hyperthreading or not. Also, it would be helpful to tell users that Core i5 CPOU have NO HT support while Core i7 do have it. Thus, enabling HT on Core i5 is a waste of resources. http://old.nabble.com/Hyperthreading-on-Core-i7s%3A-To-use-or-not-to-use--td27320293.html http://blog.stuffedcow.net/2011/08/linux-smt-aware-process-scheduling/ Finally, turbostat shows that if you on a Dual Core enable HT, your Turbo frequence will be lower that if you disable HT (note the lines with "max turbo * active cores"): # turbostat -v GenuineIntel 13 CPUID levels; family:model:stepping 0x6:2a:7 (6:42:7) 8 * 100 = 800 MHz max efficiency 28 * 100 = 2800 MHz TSC frequency 33 * 100 = 3300 MHz max turbo 4 active cores 33 * 100 = 3300 MHz max turbo 3 active cores 33 * 100 = 3300 MHz max turbo 2 active cores 35 * 100 = 3500 MHz max turbo 1 active cores core CPU %c0 GHz TSC %c1 %c3 %c6 %c7 %pc2 %pc3 %pc6 %pc7 68.32 3.33 2.79 17.36 3.31 6.17 4.84 0.00 0.00 0.00 0.00 0 0 78.19 3.35 2.79 17.65 1.98 1.41 0.77 0.00 0.00 0.00 0.00 0 2 80.60 3.35 2.79 15.23 1.98 1.41 0.77 0.00 0.00 0.00 0.00 1 1 57.15 3.31 2.79 18.38 4.63 10.92 8.91 0.00 0.00 0.00 0.00 1 3 57.34 3.31 2.79 18.19 4.63 10.92 8.91 0.00 0.00 0.00 0.00 core CPU %c0 GHz TSC %c1 %c3 %c6 %c7 %pc2 %pc3 %pc6 %pc7 61.91 3.34 2.79 24.06 2.33 5.51 6.19 0.00 0.00 0.00 0.00 0 0 64.05 3.37 2.79 33.02 0.27 1.66 0.99 0.00 0.00 0.00 0.00 0 2 85.30 3.35 2.79 11.77 0.27 1.66 0.99 0.00 0.00 0.00 0.00 1 1 43.62 3.31 2.79 31.26 4.38 9.35 11.39 0.00 0.00 0.00 0.00 1 3 54.68 3.30 2.79 20.20 4.38 9.35 11.39 0.00 0.00 0.00 0.00 core CPU %c0 GHz TSC %c1 %c3 %c6 %c7 %pc2 %pc3 %pc6 %pc7 70.15 3.33 2.79 17.97 2.28 5.86 3.74 0.00 0.00 0.00 0.00 0 0 64.81 3.32 2.79 21.84 2.71 6.28 4.36 0.00 0.00 0.00 0.00 0 2 73.38 3.32 2.79 13.28 2.71 6.28 4.36 0.00 0.00 0.00 0.00 1 1 72.27 3.33 2.79 17.32 1.84 5.44 3.13 0.00 0.00 0.00 0.00 1 3 70.16 3.33 2.79 19.43 1.84 5.44 3.13 0.00 0.00 0.00 0.00 core CPU %c0 GHz TSC %c1 %c3 %c6 %c7 %pc2 %pc3 %pc6 %pc7 65.69 3.32 2.79 26.09 1.44 4.09 2.69 0.00 0.00 0.00 0.00 0 0 52.26 3.30 2.79 34.31 2.04 6.98 4.41 0.00 0.00 0.00 0.00 0 2 63.78 3.30 2.79 22.79 2.04 6.98 4.41 0.00 0.00 0.00 0.00 1 1 76.17 3.33 2.79 20.82 0.84 1.20 0.97 0.00 0.00 0.00 0.00 1 3 70.53 3.33 2.79 26.45 0.84 1.20 0.97 0.00 0.00 0.00 0.00 ^C Have "Intel(R) Core(TM) i7-2640M CPU @ 2.80GHz". HT is said to increase power consumption and overclockers always disable HT to overclock better.
there is no turbostat utility in any stable version of pmtools. so we can't include tips on how to use it until the maintainers mark it stable. RESO LATER. we can revisit these ideas once there's a stable version of pmutils with the necessary utilities.
Re-opening and adding depend on bug #408089.
(In reply to comment #0) > Also, it would be helpful to tell users that Core i5 CPOU have NO HT support > while Core i7 do have it. Thus, enabling HT on Core i5 is a waste of > resources. Your source of information is wrong, I'm typing this infromation on a laptop with an i5 CPU and HT enabled right now. > Have "Intel(R) Core(TM) i7-2640M CPU @ 2.80GHz". HT is said to increase > power consumption and overclockers always disable HT to overclock better. Power management and optimization is a complicated task; I'm also afraid it's going to be very workload-specific. There is noone in the Gentoo's documentation project who has deep knowledge about this matter, so the best we can do is to encourage "common practice" and not override upstream's default. The web is half-full of benchmarks suggesting to leave HT enabled and half-full of those saying that it sucks completely. From that POV, it makes sense to go with any other linux distro is doing, ie. not disabling HT. As of your suggestion to use turbostat, you might be interested in (unstable) versions of powertop which can show both individual core speeds and plenty of other power-related information.
no stable version has the required utility; we can't do anything about it. and jan's notes suggest that it's not going to do a lot of good anyway.
Please re-open this bug and fix the docs, as suggested originally. Please improve the silly description of this package to include the word 'turbostat', ideally inlcude also the other 'toolnames' bundled by upstream to linux-sources. We are all wasting our times here. * sys-apps/linux-misc-apps Latest version available: 3.6-r1 Latest version installed: [ Not Installed ] Size of files: 80,367 kB Homepage: http://kernel.org/ Description: Misc tools bundled with kernel sources License: GPL-2
1. you copy-pasted instructions to the ebuild developers (from bug #408089) regarding DESC. there's nothing the GDP can do about that. 2. there's no stable version of linux-misc-apps, and it's only available on 3 arches. gentoo's official docs track stable packages. 3. since this bug was originally filed, the document in question has moved to the user-editable wiki, which means you are free to edit it.
