Messages in this thread | | | From | Bjorn Helgaas <> | Subject | Re: [RFC patch 15/15] LTTng timestamp x86 | Date | Tue, 21 Oct 2008 12:10:58 -0600 |
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On Monday 20 October 2008 04:29:07 pm H. Peter Anvin wrote: > Linus Torvalds wrote: > > > > But it's not going to solve the "hey, I have 512 CPU's, they are all on > > different boards, and no, they are _not_ synchronized to one global > > clock!". > > > > That's why I'd suggest making _purely_ local time, and then aiming for > > something NTP-like. But maybe there are better solutions out there. > > At the same time, it would definitely be nice to encourage vendors of > large SMP systems to provide a common root crystal (frequency standard) > for a single SMP domain. Preferrably a really good one, TCXO or better.
A single root crystal is nice for us software guys. But it often also turns into a single point of failure, which the hardware guys are always trying to eliminate. So I think multiple crystals are inevitable for the really large machines.
Bjorn
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