From: fser@code-libre.org (François)
To: kernelnewbies@lists.kernelnewbies.org
Subject: Stupid question regarding bogomips and udelay()
Date: Mon, 1 Aug 2016 11:47:53 +0200 [thread overview]
Message-ID: <20160801094752.37wpzdxw7e3den5b@sith> (raw)
In-Reply-To: <20160801083607.02157a64@fujitsu>
Hello, that's an interesting question!
I'm currently reading the same book, but you've read more than me so far :)
On Mon, Aug 01, 2016 at 08:36:07AM +0300, Aleksander Alekseev wrote:
> * bogomips value (see `cat /proc/cpuinfo`) is determined only once
> during system boot
As far as I know, I is (was?) the case.
> It's my understanding that it shouldn't work. CPU frequency actually
> changes manually (see cpufrequtils) and/or automatically depending for
> instance on laptop's current battery charge. There is also such a nasty
> thing as Intel Turbo Boost. In other words actual MIPS could be higher
> or lower than measured MIPS. So udealy() can't guarantee anything.
Makes sense. Do you have such machine? Did you try to get bogomips and then
reduce your CPU count / speed and get that number again?
Maybe this value is now dynamic.
Also, did you actually try udealay() in high/low frequency to see wether you
see an actual difference between runs?
Sorry I don't have final answers!
--
Fran?ois
next prev parent reply other threads:[~2016-08-01 9:47 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-01 5:36 Stupid question regarding bogomips and udelay() Aleksander Alekseev
2016-08-01 9:47 ` François [this message]
2016-08-02 8:27 ` Aleksander Alekseev
2016-08-03 1:20 ` Daniel.
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