Re: [RFC patch 08/18] cnt32_to_63 should use smp_rmb()

David Howells
2008-11-07T17:05:52Z

Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:

> First off, using this macro with get_cycles() is simply buggy, because the
> macro expects _perfect_ order of timestamps, no skew whatsoever, or
> otherwise time could jump.

Erm... Why can't I pass it get_cycles()? Are you saying that sched_clock()
in MN10300 is wrong for it's use of get_cycles() with cnt32_to_63()?

> __x.lo = readl(cnt_lo); /* mmio read */

readl() might insert an extra barrier instruction. Not only that, io_addr
must be unsigned long.

David