Date: Thu, 14 Aug 2003 20:17:33 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: "Adam Migus" <adam@migus.org> Cc: current@freebsd.org Subject: Re: make buildkernel hang with SCHED_ULE Message-ID: <16188.9885.685630.274388@grasshopper.cs.duke.edu> In-Reply-To: <52019.192.168.4.2.1060657784.squirrel@mail.migus.org> References: <52019.192.168.4.2.1060657784.squirrel@mail.migus.org>
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Adam Migus writes: > Folks, > While doing some performance analysis (doing make -j5 buildkernel) > on a set of 14 kernels I've hit one using the SCHED_ULE scheduler > that hangs. It happens every time but not necessarily in the same > place in the make. > <...> > The hardware is a dual Xeon box. The kernel is SMP w/ SCHED_ULE > instead of SCHED_4BSD, the options required for diskless and the > following two options: You have machdep.hlt_logical_cpus: 1 in your sysctl output. [BTW, lots of people read this mail via the web archives at http://docs.freebsd.org/cgi/getmsg.cgi?fetch=1073654+0+current/freebsd-current, where its impossible to view mime; it would be MUCH better for us if appended things like stack traces and sysctl output rather then scrambling them for no reason] SCHED_ULE is incompatible with halting logical CPUs. Something about it does't know the core isn't running, so it schedules a job there which never runs, and then it gets confused. When I boot a 1 CPU P4 with an SMP kernel and machdep.hlt_logical_cpus=1, it hangs before making it to multiuser mode.. Try setting machdep.hlt_logical_cpus=0 (via sysctl now, and in /boot/loader.conf so it doesn't happen again). Drew
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