Messages in this thread | | | Date | Sat, 28 Oct 2006 22:16:29 +0200 | From | Willy Tarreau <> | Subject | Re: AMD X2 unsynced TSC fix? |
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On Sat, Oct 28, 2006 at 12:42:45PM -0700, thockin@hockin.org wrote: > On Sat, Oct 28, 2006 at 09:32:18PM +0200, Willy Tarreau wrote: > > > Was the problem that they were not synced at poweron or that they would > > > drift due to power-states? > > > > They resynced at power up, but would constantly drift. I don't even know > > if it was caused by power states. When the machine was loaded, a single > > task moving across the cores could see its time jump back and forth > > several times a second by an offset sometimes close to +2/-2s. > > That sounds like C1, to me.
OK.
> > > Did you try running with idle=poll, to avoid ever entering C1 state (hlt)? > > > > Yes, I remember trying such things. I also tried 'nohlt', completely > > disabling power management, including ACPI, etc... I also tried vanilla > > kernels as well as severely patched ones, but the problem remained the > > same in all circumstances, that only 'notsc' could solve. > > That's exceedingly strange. On my dual-socket dual-core, I can get > roughly synced TSCs (no appreciable drift) by just using idle=poll.
As I said in another mail, I thought I won by running several busy loops in parallel to the load, which prevented the system from either halting or slowing down. But it was OK for a few minutes only and started going mad again.
> If that did not work for you, I'd really want to poke at the system more.
The machine was returned to the supplier and for other reasons, we switched to a different maker for the about 20 machines (and all single-core). I've read somewhere that there's already a second version of the sun x2100, I don't know if it still exhibits the problem. Maybe at least they've fixed the BIOS to report the HPET.
> > BTW, I've just found a remain of dmesg capture after boot in case you'd > > like to look for anything in it. > > A dmesg won't be that useful, I'd actually have to poke at the system.
OK. I don't know if anyone there has one at hand, as I don't have it anymore.
Regards, Willy
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