Re: [PATCH] x86: Export tsc related information in sysfs

From: Ingo Molnar
Date: Mon May 17 2010 - 20:01:42 EST

* Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> wrote:

> OK, well ignoring the metaphor, it's clear we
> disagree on a point that neither one of us can
> prove: You think your decision to avoid sharing
> kernel information will stop system programmers
> from using rdtsc, and I think some are going to use
> rdtsc anyway and blame Linux when something
> eventually and silently breaks.

Applications can do various unreliable things, the
kernel cannot do anything about that.

The point is for the kernel to not be complicit in
practices that are technically not reliable.

So the kernel wont 'signal' that something is safe to
use if it is not safe to use.

One suggestion in this thread makes sense i think: to
signal via sysfs that gettimeofday is slow.

Plus lets hope that we really can figure out a fast,
TSC based gettimeofday implementation. If that is
possible then user-space will get a fast gettimeofday
right out of box.


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