Messages in this thread | | | Date | Wed, 21 Sep 2005 13:17:13 -0700 | From | Andrew Morton <> | Subject | Re: [discuss] Re: [PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs |
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Andi Kleen <ak@suse.de> wrote: > > 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.
You mean a single `hlt' instruction? I guess that rules out resyncing them.
> 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)
That's a really big drawback. Will this affect many CPU types?
If the user was prepared to use `idle=poll' then they could get their fast gettimeofday() back, perhaps.
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