Messages in this thread | | | Subject | [PATCH] preempt-kernel on 2.4.19-pre2-ac2 bugfix | From | Robert Love <> | Date | 04 Mar 2002 19:23:10 -0500 |
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The same schedule_tail bug affecting 2.5 affects 2.4 with O(1). I.e., 2.4.19-pre2-ac2.
In recent O(1) scheduler releases, an optimization was made that removed schedule_tail from UP kernels. This causes the initial preempt_count of a new task, which starts at 1, to never decrement to zero and thus never become preemptible. CONFIG_PREEMPT requires schedule_tail, too.
Users of 2.4+O(1)+preempt (i.e. -ac) should use this patch:
http://www.kernel.org/pub/linux/kernel/people/rml/preempt-kernel/v2.4/preempt-kernel-rml-2.4.19-pre2-ac2-2.patch
instead. Thanks to everyone who pointed out the lousy performance. Enjoy,
Robert Love
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