Re: [patch] Real-Time Preemption, -RT-2.6.9-rc4-mm1-U7

[Rui Nuno Capela]

Ingo Molnar wrote:
>
> i have released the -U7 Real-Time Preemption patch:
>
>   http://redhat.com/~mingo/realtime-preempt/realtime-preempt-2.6.9-rc4-mm1-U7
>

With U7 I'm now able to boot and go all the way into X/KDE with a
SMP+PREEMPT_REALTIME configured kernel (config.gz attached) and reboot
into it, again and again. Things are getting better, really, but ...

Overall behavior is still unreliable. Many things stop functioning once
and for good (until reboot). The shutdown sequence is also prone to busy
hanging.

As an aside, my greatest complaint is that jackd -R doesn't work at all:

JACK: unable to mlock() port buffers: Cannot allocate memory
jack_create_thread: error -1 switching current thread to rt for
inheritance: Unknown error 4294967295
cannot start watchdog thread
cannot load driver module alsa

Another example, and one of the very few that were verbose on dmesg, while
accessing the floppy disk (subfs mounted), I got:

kernel BUG at fs/buffer.c:2702!
invalid operand: 0000 [#1]
PREEMPT SMP
Modules linked in: nls_iso8859_15 nls_cp860 vfat fat nls_base snd_seq
usbhid ehc
i_hcd intel_mch_agp agpgart uhci_hcd mga snd_usb_usx2y snd_usb_lib
snd_rawmidi s
nd_seq_device snd_hwdep snd_intel8x0 snd_ac97_codec snd_pcm snd_timer snd
soundc
ore snd_page_alloc evdev sk98lin w83781d i2c_sensor i2c_isa i2c_i801
i2c_core wa
com usbcore subfs dm_mod
CPU:    0
EIP:    0060:[<c015a9c2>]    Not tainted VLI
EFLAGS: 00010246   (2.6.9-rc4-mm1-RT-U7.0smp)
EIP is at submit_bh+0x119/0x126
eax: 00000004   ebx: f16d683c   ecx: 00000000   edx: f12e2000
esi: f16d683c   edi: 00000000   ebp: f12e3d90   esp: f12e3d78
ds: 007b   es: 007b   ss: 0068   preempt: 00000001
Process submountd (pid: 11393, threadinfo=f12e2000 task=f6116950)
Stack: 00000000 00000200 00000000 f16d683c fffffffb f64b0800 f12e3da4
c01587e3
       00000000 f16d683c f4675000 f12e3db8 c0158ab1 f16d683c 00000000
00000200
       f12e3e34 f8c7e85b f673d500 00000000 00000200 f4675148 f12e3de8
c02ca60c
Call Trace:
 [<c0105235>] show_stack+0xaf/0xb7 (28)
 [<c01053c5>] show_registers+0x168/0x1dd (56)
 [<c01055ce>] die+0x107/0x18f (64)
 [<c0105aee>] do_invalid_op+0x109/0x10b (188)
 [<c0104e7d>] error_code+0x2d/0x38 (92)
 [<c01587e3>] __bread_slow+0x60/0xb2 (20)
 [<c0158ab1>] __bread+0x33/0x39 (20)
 [<f8c7e85b>] fat_fill_super+0xe6/0x76c [fat] (124)
 [<f8c43d70>] vfat_fill_super+0x30/0x67 [vfat] (32)
 [<c015d220>] get_sb_bdev+0xf1/0x147 (72)
 [<f8c43dd5>] vfat_get_sb+0x2e/0x31 [vfat] (28)
 [<c015d492>] do_kern_mount+0xa5/0x15a (44)
 [<c0172f0d>] do_new_mount+0x71/0xab (52)
 [<c01735e3>] do_mount+0x184/0x1ae (116)
 [<c0173a21>] sys_mount+0x97/0xd6 (48)
 [<c01043b9>] sysenter_past_esp+0x52/0x71 (-8124)
preempt count: 00000002
. 2-level deep critical section nesting:
.. entry 1: _spin_lock_irqsave+0x17/0x70 / (die+0x3f/0x18f)
.. entry 2: print_traces+0x16/0x4c / (show_stack+0xaf/0xb7)

Code: 24 e8 28 08 00 00 8b 45 f0 83 c4 0c 5b 5e 5f 5d c3 0f 0b 8d 0a 86 ea
2d c0 e9 14 ff ff ff 0f 0b 8f 0a 86 ea 2d c0 e9 1c ff ff ff <0f> 0b 8e 0a
86 ea 2d c0 e9 04 ff ff ff 55 89 e5 57 56 31 f6 53
 <3>subfs: submountd execution failure. Error 11


Think it's too early to party, eh? :)
-- 
rncbc aka Rui Nuno Capela
rncbc@xxxxxxxxx

Attachment: config-2.6.9-rc4-mm1-RT-U7.0smp.gz
Description: GNU Zip compressed data