[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: [PATCH] clocksource=tsc
On 15/7/08 15:44, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote: > Hmmm... One thing I was trying to do with the special > casing in get_s_time() was to avoid using a dynamically > changing scaling (t->tsc_scale). If I'm not mistaken, > t->tsc_scale is recalculated every EPOCH and thus is > a potential source of stime jitter. Seems unnecessary > just to make the code look cleaner. My patch disables the per-epoch calibration. Actually in this mode of operation we hardly need a platform timer *at all*. The idea is that we let the TSCs free-run, because we know they will behave. Returning to 32-bit read_counter(), and having NULL read_counter when clocksource=tsc would be another possibility... > One other nit: Especially if the above is changed, do > you really prefer a strcmp vs a global variable (or > checking for size == 64) for determining if the tsc > is the platform timer? It's hidden in a macro and it's called very rarely. So I think it's fine. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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