Re: hw.ncpuonline

Otto said:
> it makes certain types of attack easier.

I can confirm this. I already crossed the river and I came back to the defaults.
Then "only the sky can know" about the possible attacks one can face.
I guess the defaults are to clarify "what there is under the sky".
And the metaphor of the sky makes much sense to my own system config.

There are some tricks to increment performances beyond what you just dicovered.

Eg: depending on amount of ram you own.. to employ some - and only some - gb of that
dimm stuff :D.. and depending on what you is your storage device, you can think to speed up
this latter by placing on ram the /tmp. Sorry if Im not technical enough here, you can
point the man to "fstab" or I'm sure someone else here can decode it to you.

However, there are some cons. For example some software packages don't bear this ram move
ie. MariaDB is one of those packages (aaah, bug! ;-)
-- Daniele Bonini

Feb 1, 2023 07:45:48 Otto Moerbeek <otto@drijf.net>:

> On Wed, Feb 01, 2023 at 07:35:16AM +0100, Janne Johansson wrote:
>
>> Den ons 1 feb. 2023 kl 03:08 skrev Justin Muir <ve7utm@gmail.com>:
>>> I've got an AMD A10 with 4 cores and only 2 are online. I'm not sure how to
>>> enable the other 2.
>>>
>>> hw.ncpufound=4 btw
>>> Any ideas out there?
>>
>> OpenBSD disables hyperthreading (or symmetric multithreading, smt), so
>> if your "4-core" cpu is actually 2 real cores and 2 hyperthreads, then
>> this sounds perfectly reasonable.
>>
>> For example, this box of mine (not the same cpu, but still), it looks like this:
>>
>> hw.ncpufound=8
>> hw.smt=0
>> hw.ncpuonline=4
>>
>> so I get the 4 real cores running out of possibly 8.
>>
>> --
>> May the most significant bit of your life be positive.
>>
>
> It is posible to enable symmetric multithreading, at your own risk as
> it makes certain types of attack easier. Often it does not increase
> performance.
>
> sysctl hw.smt=1
>
> See man sysctl.conf for a permanent solution.
>
>     -Otto