Re: [RFC patch] Use IPI_shortcut for lapic timer broadcast

From: Ingo Molnar
Date: Mon Jun 29 2009 - 03:21:11 EST



* Luming Yu <luming.yu@xxxxxxxxx> wrote:

> Hello,
>
> We need to use IPI shortcut to send lapic timer broadcast
> to avoid the latency of sending IPI one bye one on systems with many
> logical processors when NO_HZ is disabled.
> Without this patch,I have seen upstream kernel with RHEL 5 kernel
> config boot hang .

hm, that might be a valid optimization - but why does the lack of
this optimization result in a hang?

Ingo
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