Messages in this thread | | | Subject | Re: [PATCH] linux-2.5.66_monotonic-clock_A3 | From | john stultz <> | Date | 31 Mar 2003 10:39:09 -0800 |
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On Fri, 2003-03-28 at 23:57, Andi Kleen wrote: > john stultz <johnstul@us.ibm.com> writes: > > > + do { > > + seq = read_seqbegin(&xtime_lock); > > + ret = timer->monotonic_clock(); > > + } while (read_seqretry(&xtime_lock, seq)); > > Why does it need to check xtime lock ? xtime should be independent > of the monotonic time because it can be changed.
Ok, fair enough. I was using the xtime lock to protect monotonic_base in (updated in mark_offset()), but since that isn't obvious I should be more explicit and use a different lock.
> Also doing seqlocks around hardware register reads is quite nasty, > because a hardware register read can be hundreds of cycles and you're > very likely to get retries. If you really need a seqlock I would > move it into the low level function and do it after the hardware access. > But as far as I can see it can be just removed.
I should be able to use a regular rwlock w/o troubles. I change that and resubmit.
thanks for the feedback! -john
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