On Tuesday 13 June 2006 17:36, John Birrell wrote: > On Tue, Jun 13, 2006 at 02:15:43AM +0000, John Birrell wrote: > > With the development as it stands at the moment, take care using the FBT > > provider because you can easily cause the system to go kaboom. I'm still > > trying to track down the problems there. It's not in FBT itself -- just > > the fact that the DTrace probe context isn't allowed to call anything that > > FBT can instrument. If that happens you will either get a reboot or a > > double fault will leave you in kdb. I recommend only enabling a few FBT > > probes at a time just so you know which ones could cause a fault. There is > > no point telling me that you enabled fbt::: and the system went kaboom! > > With the FBT provider as it now stands and using this script: > > fbt:::entry > { > _at_[probefunc] = count(); > } > > the output after a buildworld is listed below. Check out the number of > calls to critical_enter and critical_exit (which are listed at the bottom)! > And for comparison, check the hardclock() count which relects 1000 Hz. Those functions are called a lot as every spinlock ends up calling them (including sched_lock, turnstile chain locks, sleepqueue locks, etc.) One thing I found odd is: > cpu_set_fork_handler 608 > kthread_create 608 > kthread_exit 608 We created and destroyed 608 kernel threads during a buildworld?? This doesn't seem right. Were you doing the buildworld over NFS? -- John Baldwin <jhb_at_FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.orgReceived on Wed Jun 14 2006 - 12:25:54 UTC
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