Messages in this thread | | | Date | Wed, 21 Sep 2005 17:04:04 +0200 | From | Andi Kleen <> | Subject | Re: [discuss] Re: [PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs |
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On Wed, Sep 21, 2005 at 10:15:08AM -0500, Ray Bryant wrote: > On Tuesday 20 September 2005 23:03, Daniel Jacobowitz wrote: > > > > > FYI, at least I have reproduced this without powernow loaded. > > There are cases that we are aware of where the TSC will count slower while the > processor is halted. This can make TSC's get out of sync on dual cores.
Ok thanks for the confirmation. I guess John's patch is ok then. Drawback is much slower to extremly slow gettimeofday (depending if the chipset/BIOS has usable HPET, most seem not to)
> > I wonder if you can reproduce this problem while also running a pair of cpu > bound tasks on your dual core box. If you can't, then this is the culprit. > > In general, however, on multisocket systems, you can't depend on TSC's being > synchronized between sockets, so all of this is moot. We just have to deal > with it.
We handle this, but single socket dual core was special cased because I was told previously it should be ok.
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