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Add a comment on why inlining critical_enter() may not be a good idea

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for the general case.

Reviewed by:	bde
MFC after:	1 week
This commit is contained in:
Attilio Rao 2012-12-09 04:54:22 +00:00
parent 25b5bb4c1b
commit e68ccbe85e
1 changed files with 6 additions and 0 deletions
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6
sys/kern/kern_switch.c
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@ -176,6 +176,12 @@ retry:
/*
* Kernel thread preemption implementation. Critical sections mark
* regions of code in which preemptions are not allowed.
*
* It might seem a good idea to inline critical_enter() but, in order
* to prevent instructions reordering by the compiler, a __compiler_membar()
* would have to be used here (the same as sched_pin()). The performance
* penalty imposed by the membar could, then, produce slower code than
* the function call itself, for most cases.
*/
void
critical_enter(void)