Messages in this thread | | | Date | Tue, 21 Mar 2006 00:33:07 -0500 | From | "Albert Cahalan" <> | Subject | Re: gettimeofday order of magnitude slower with pmtimer, which is default |
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bert hubert writes:
> Not only is the pm timer slow by design, it also needs to be read > multiple times to work around a bug in certain hardware. > > What is new is that this option is now dependent on CONFIG_EMBEDDED. > Unless you select this option, the PM Timer will always be used.
Good. Fast but horribly buggy is NOT acceptable as a default. Go ahead and tweak the settings on YOUR system. Run Gentoo.
I wasted a lot of time trying to figure out why my clock ran about 1.414 (yes, square root of two) times faster than proper. It turns out that a normal dual-core AMD box has TSCs that run at randomly varying and fully independant rates. Before I found a post to linux-kernel by an AMD employee explaining this, my thought was that I was probably missing clock ticks from the BIOS going into SMM mode. That was the problem the previous time I had clock problems. (so I reduced HZ to 100, etc.)
I'm sure lots of people would never figure out why their clock is running 41.4% faster than normal. They'd live with it, using a physical clock mounted on the wall, or switch to a different OS. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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