Re: 2.6.25-rc5-git6: Reported regressions from 2.6.24
From: Gabriel C
Date: Sat Mar 22 2008 - 11:13:50 EST
Thomas Gleixner wrote:
> On Sat, 22 Mar 2008, Gabriel C wrote:
> > Now some time later CPU1 gets woken by an interrupt/IPI and runs the
>>> timer wheel. At this point the pm_timer which is the reference clock
>>> has already wrapped around, so the watchdog thinks that there is a
>>> huge time difference and marks the TSC unstable.
>>>
>>> Aside of that watchdog issue this also affects the other users of
>>> add_timer_on(): e.g. queue_delayed_work_on().
>>>
>>> Can you please apply the patch below and verify it with Andi's
>>> watchdog patch applied ?
>>
>> Did that , git head , Andi's + your patch but TSC is still marked unstable.
>
> Doh, stupid me. We do not reevaluate the timer wheel, when we just
> wake up via the smp_reschedule IPI when the resched flag on the other
> CPU is not set. That's a separate vector which is not going through
> irq_enter() / irq_exit().
>
> Does the patch below solve the problem ?
With this one TSC is fine but now I get a warning on boot :
..
[ 0.041037] ------------[ cut here ]------------
[ 0.041052] WARNING: at arch/x86/kernel/smp_32.c:562 native_smp_call_function_mask+0x23/0x11e()
[ 0.041074] Modules linked in:
[ 0.041087] Pid: 1, comm: swapper Not tainted 2.6.25-rc6-00243-g028011e-dirty #12
[ 0.041107] [<c011b51c>] warn_on_slowpath+0x40/0x65
[ 0.041128] [<c012b543>] autoremove_wake_function+0xd/0x2d
[ 0.041148] [<c033f28b>] schedule_timeout+0x13/0x99
[ 0.041167] [<c011690d>] __wake_up+0x29/0x39
[ 0.041182] [<c011690d>] __wake_up+0x29/0x39
[ 0.041197] [<c0128769>] call_usermodehelper_exec+0x97/0xa2
[ 0.041214] [<c010dff4>] native_smp_call_function_mask+0x23/0x11e
[ 0.041233] [<c01d4a66>] kobject_uevent_env+0x346/0x368
[ 0.041251] [<c010e46d>] smp_call_function_single+0x50/0x6f
[ 0.041268] [<c01336d2>] tick_nohz_rescan_timers_on+0x27/0x2b
[ 0.041287] [<c013109f>] clocksource_register+0x162/0x174
[ 0.041306] [<c0436203>] kernel_init+0x126/0x25e
[ 0.041322] [<c011943d>] schedule_tail+0x17/0x44
[ 0.041337] [<c0103c7a>] ret_from_fork+0x6/0x1c
[ 0.041353] [<c04360dd>] kernel_init+0x0/0x25e
[ 0.041367] [<c04360dd>] kernel_init+0x0/0x25e
[ 0.041381] [<c01049ab>] kernel_thread_helper+0x7/0x10
[ 0.041397] =======================
[ 0.041417] ---[ end trace ca143223eefdc828 ]---
..
Full dmesg there -> http://frugalware.org/~crazy/dmesg/dmesg_tsc
>
> Thanks,
>
> tglx
>
Gabriel
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