Re: [PATCH 1/4] mm: introduce compaction and migration for virtio ballooned pages

From: Andi Kleen
Date: Tue Jun 26 2012 - 16:34:02 EST


> How is the compiler meant to optimise away "cond" if it's a function
> call?

Inlines can be optimized away. These tests are usually inlines.

> What did I miss? If nothing, then I will revert this particular change
> and Rafael will need to be sure his patch is not using VM_BUG_ON to call
> a function with side-effects.

Do you have an example where the code is actually different,
or are you just speculating?

FWIW for my config both generates the same code:

size vmlinux-andi-vmbug vmlinux-vmbug-nothing
text data bss dec hex filename
11809704 1457352 1159168 14426224 dc2070 vmlinux-andi-vmbug
11809704 1457352 1159168 14426224 dc2070 vmlinux-vmbug-nothing

-Andi
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