Re: [patch] Real-Time Preemption, -VP-2.6.9-rc4-mm1-U3

[Adam Heath]

On Sat, 16 Oct 2004, Ingo Molnar wrote:

>
> * Adam Heath <doogie@xxxxxxxxxx> wrote:
>
> > On Fri, 15 Oct 2004, Ingo Molnar wrote:
> >
> > >
> > > i have released the -U3 PREEMPT_REALTIME patch:
> > >
> > >   http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.9-rc4-mm1-U3
> >
> > scheduling while atomic: postmaster/0x04000002/3175
> > caller is cond_resched+0x53/0x70
> >  [<c01069f7>] dump_stack+0x17/0x20
> >  [<c027b457>] schedule+0x517/0x550
> >  [<c027b9c3>] cond_resched+0x53/0x70
> >  [<c012cdc7>] _mutex_lock+0x17/0x40
> >  [<c012ce18>] _mutex_lock_irqsave+0x8/0x10
> >  [<c01b21ae>] avc_has_perm_noaudit+0x2e/0x180
> >  [<c01b2335>] avc_has_perm+0x35/0x68
> >  [<c01b79ca>] ipc_has_perm+0x6a/0x80
> >  [<c01ab716>] semctl_main+0xa6/0x410
> >  [<c01abcad>] sys_semctl+0xad/0xb0
> >  [<c010bafd>] sys_ipc+0xad/0x250
> >  [<c0105bff>] syscall_call+0x7/0xb
>
> thanks - that's the IPC code that is not converted over from RCU yet.
>
> a suggestion for future testing: please enable PREEMPT_TIMING for the
> next kernels you build, it will print such entries at the end of
> stacktraces:

adam@gradall:~/kernel/gradall/linux-2.6.9-rc4-mm1-U3$ grep PREEMPT /boot/config-2.6.9-rc4-mm1-vp-u3
CONFIG_PREEMPT_TIMING=y
CONFIG_PREEMPT=y
CONFIG_PREEMPT_BKL=y
CONFIG_PREEMPT_VOLUNTARY=y
CONFIG_PREEMPT_SOFTIRQS=y
CONFIG_PREEMPT_HARDIRQS=y
CONFIG_PREEMPT_REALTIME=y
CONFIG_DEBUG_PREEMPT=y
adam@gradall:~/kernel/gradall/linux-2.6.9-rc4-mm1-U3$ grep LATENCY /boot/config-2.6.9-rc4-mm1-vp-u3
# CONFIG_LATENCY_TRACE is not set

So, it must not be working.

I'm recompiling now to enable LATENCY_TRACE, however.

>  preempt count: 2
>  entry 1: cpu_idle+0x38/0x90 / (start_kernel+0x1ac/0x1f0)
>  entry 2: _spin_lock+0x22/0x80 / (timer_interrupt+0x1b/0x130)

There were no preempt count lines anywhere.

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