Okay maybe I should wait for dtrace to be enabled and working by default. 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.
Regards, Stephan 2014-08-22 18:29 GMT+02:00 Taylor R Campbell <riastr...@netbsd.org>: > Date: Fri, 22 Aug 2014 17:59:37 +0200 > From: Stephan <stephan...@googlemail.com> > > Has anybody an idea on this or how to track this down? At the moment, > I can't even enter ddb using Strg+Alt+Esc keys for some reason. I've > also seen people playing with dtrace but that doesn't seem to be > included. > > Dtrace may be a good idea. You can use it by > > (a) using a kernel built with `options KDTRACE_HOOKS', > (b) using a userland built with MKDTRACE=yes, > (c) modload /stand/ARCH/VERSION/solaris.kmod > modload /stand/ARCH/VERSION/dtrace.kmod > modload /stand/ARCH/VERSION/fbt.kmod > modload /stand/ARCH/VERSION/sdt.kmod > (d) mkdir /dev/dtrace && mknod /dev/dtrace/dtrace c dtrace > > (Yes, this is too much work. Someone^TM should turn it all on by > default for netbsd-7...!) > > From the lockstat output it looks like there's a lot of use of > mntvnode_lock, which suggests this may be related to hannken@'s vnode > cache changes. Might be worthwhile to sample stack traces of > vfs_insmntque, with something like > > dtrace -n 'fbt::vfs_insmntqueue:entry { @[stack()]++ }' > > or perhaps sample stack traces of the mutex_enters of mntvnode_lock.