Messages in this thread | | | Date | Mon, 23 May 2005 10:40:46 -0700 | From | Ashok Raj <> | Subject | Re: [discuss] Re: [patch 0/4] CPU hot-plug support for x86_64 |
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On Mon, May 23, 2005 at 07:12:12PM +0200, Andi Kleen wrote: > > The only other workable alternate would be to use the stop_machine() > > like thing which we use to automically update cpu_online_map. This means we > > execute a high priority thread on all cpus, bringing the system to knees before > > That is not nice agreed. > > > just adding a new cpu. On very large systems this will definitly be > > visible. > > I still dont quite get it why it is not enough to keep interrupts > off until the CPU enters idle. Currently we enable them shortly > in the middle of the initialization (whcih is already dangerous > because interrupts can see half initialized state like out of date TSC), > but I hope to get rid of that soon too. With the full startup > in CLI would you problems be gone? >
I think so, if we can ensure none is delivered to the partially up cpu we probably are covered.
Iam not a 100% sure about above either, if the smp_call_function is started with 3 cpus initially, and 1 just came up, the counts in the smp_call data struct could be set to 3 as a result of the new cpu received this broadcast as well, and we might quit earlier in the wait.
sending to only relevant cpus removes that ambiquity.
[Vatsa would know this better, since was the corner case man then :-)] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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