Date: Sun, 24 Aug 2014 15:26:46 +0200 From: Stephan <[email protected]>
Okay maybe I should wait for dtrace to be enabled and working by default. Well, plugh. Every one of the instructions I rattled off from memory was slightly wrong, and apparently the default amd64 kernel doesn't have enough KVA reserved to even load the dtrace modules. Here are the right instructions: https://wiki.netbsd.org/tutorials/how_to_enable_and_run_dtrace/ And NKL2_KIMG_ENTRIES has to be bumped from 16 to 32 in sys/arch/amd64/include/pmap.h for the kernel to have enough KVA to load the modules -- something we definitely ought to fix pronto. As I said, I could´t even enter ddb. Otherwise I could have placed a breakpoint on mutex_enter() to get example stack traces. I wonder, though, if this really can be related to locking as this test is basically single-threaded. Could be, but I seem to recall we already isolated another vcache-related performance problem to excessive lock/unlock cycles in a single-threaded test.
