Re: [RFC patch 15/15] LTTng timestamp x86

On Monday 20 October 2008 04:29:07 pm H. Peter Anvin wrote:

Linus Torvalds wrote:

quoted

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