On Thu, Jan 03, 2008 at 01:56:58AM +0100, Arjan van de Ven wrote: > Subject: move WARN_ON() out of line > From: Arjan van de Ven <[EMAIL PROTECTED]> > CC: Ingo Molnar <[EMAIL PROTECTED]> > CC: Andrew Morton <[EMAIL PROTECTED]> > > A quick grep shows that there are currently 1145 instances of WARN_ON > in the kernel. Currently, WARN_ON is pretty much entirely inlined, > which makes it hard to enhance it without growing the size of the kernel > (and getting Andrew unhappy). > > This patch moves WARN_ON() out of line entirely. I've considered keeping > the test inline and moving only the slowpath out of line, but I decided > against that: an out of line test reduces the pressure on the CPUs > branch predictor logic and gives smaller code, while a function call > to a fixed location is quite fast. Likewise I've considered doing something > similar to BUG() (eg use a trapping instruction) but that's not really > better (it needs the test inline again and recovering from an invalid > instruction isn't quite fun).
Hi Arjan, I've got a couple of patches in -mm at the moment that introduces __WARN() and uses that (and lets architectures override __WARN, since for example powerpc does use trapping instructions similarly to BUG()). The two patches in question are: bugh-remove-have_arch_bug--have_arch_warn.patch powerpc-switch-to-generic-warn_on-bug_on.patch Care to do this incrementally on top of that instead? I.e. call do_warn_on() from the asm-generic/bug.h __WARN() instead. -Olof -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/