Mark Kettenis <mark.kette...@xs4all.nl> wrote:

> But maybe the default rdtsc() should include the lfence.  And then we
> could have rdtsc_unordered() for this cases that don't care about
> ordering.

Right.

But I don't like the word 'order', because it is too vague.  There
are layers of ordering, speculation, asyncronous execution, etc.
and lfence just deals with some of them.

> As I wrote in my first mail, cpu_rnd_messybits() may want to use that.
> And maybe one of the network stack people should investigate what the
> impact of having the fence in the timecounter is?

cpu_rnd_messybits is indifferent.  It is amusing to capture some
speculation side effect, but if we don't, it isn't the end of the world.
A few days ago, we didn't even know this aspect existed...

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