Re: [PATCH] Prevent users from disabling tickless

From: Serge Belyshev
Date: Sun Jan 02 2011 - 05:59:56 EST


Matthew Wilcox <matthew@xxxxxx> writes:

> Disabling NO_HZ has a serious negative effect on performance -- an extra
> 70us per I/O. Prevent users from deselecting it.

This is rather non-trivial change.

The common wisdom was that NO_HZ=y *adds* overhead, not removes it.
Thus, I propose:

(1) Retaining and elaborating the help text.
(2) Allow user to change the default.
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