--On 20 October 2006 13:47 +0100 Robert Watson <[EMAIL PROTECTED]> wrote:
I'm just a little hesitant to put it all in, and end up with a machine
that's 80% slower :(
Depends a lot on your workload. WITNESS used to really, really slow
things down for kernel lock intensive workloads (VFS especially); now it
just really slows things down. INVARIANTS overhead is generally
measurable, but for most workloads it is likely <20%. The place
INVARIANTS hits you is when the kernel is allocating and freeing lots of
memory, during which INVARIANTS will be scrubbing and checking for use
after free, etc. It's worth running with WITNESS when debugging
deadlocks if possible, because it is, essentially, a deadlock debugging
tool. A moderate number of people run with INVARIANTS in production, but
you generally don't want to do that with WITNESS.
Well this is happening on an almost daily basis for me, so I threw
everything in. I'd rather have lousy performance for a couple of days - and
get all the info needed to fix the problem, than fsck a terrabyte, and mop
up after a hung machine daily ;)
Thanks for the replies, crossing fingers now :)
-Karl
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