CCing Jan Blunck...
On Tue, Mar 04, 2008 at 09:52:10AM +0100, Martin Schwidefsky wrote:
> Um, why? We have a reason to force the deadline scheduler, our
> performance test have shown that the deadline scheduler get the highest
> throughout out of the storage subsystems which are used with the
> machines.
Is this still the case? I saw the commit from ~2005 that said that was the
case, but CFQ got a ton of changes since then.
Ok, I'll redo the patch to not make the system halt when the deadline
scheduler cannot be loaded.
I compiled the kernel without deadline, and the dasd code exists the old
scheduler (CFQ), fails to load the new one (deadline), and then things just
hang - with one of these (sorry about the weird chars - I copy & pasted it
from a 3270 console):
dasd(eckd): 0.0.0151: 3390/0A(CU:3990/01) Cyl:3338 Head:15 Sec:224
------------� cut here ¨------------
Badness at kernel/mutex.c:134
Modules linked in: dasd_eckd_mod dasd_mod
CPU: 0 Not tainted 2.6.25-rc3 #9
Process exe (pid: 538, task: 000000000d172000, ksp: 000000000d21ef88)
Krnl PSW : 0404000180000000 000000000022fb5c (mutex_lock_nested+0x2a4/0x2cc)
R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:0 PM:0 EA:3
Krnl GPRS: 0000000000024218 000000000076fc78 0000000000000000 000000000000000f
000000000022f92e 0000000000449898 000000000f921c00 000003e000162590
00000000001539c4 000000000d172000 070000007fffffff 000000000d21f400
000000000f8f2560 00000000002413f8 000000000022fb44 000000000d21f400
Krnl Code: 000000000022fb50: bf2f1000 icm %r2,15,0(%r1)
000000000022fb54: a774fef6 brc 7,22f940
000000000022fb58: a7f40001 brc 15,22fb5a
>000000000022fb5c: a7f4fef2 brc 15,22f940
000000000022fb60: c0e5fffa112a brasl %r14,171db4
000000000022fb66: 1222 ltr %r2,%r2
000000000022fb68: a784fedb brc 8,22f91e
000000000022fb6c: c010002a0086 larl %r1,76fc78
Call Trace:
(�<000000000022f92e>¨ mutex_lock_nested+0x76/0x2cc)
�<00000000001539c4>¨ elevator_exit+0x38/0x80
�<0000000000156ffe>¨ blk_cleanup_queue+0x62/0x7c
�<000003e0001d5414>¨ dasd_change_state+0xe0/0x8ec �dasd_mod¨
�<000003e0001d5cae>¨ dasd_set_target_state+0x8e/0x9c �dasd_mod¨
�<000003e0001d5f74>¨ dasd_generic_set_online+0x160/0x284 �dasd_mod¨
�<000003e00011e83a>¨ dasd_eckd_set_online+0x2e/0x40 �dasd_eckd_mod¨
�<0000000000199bf4>¨ ccw_device_set_online+0x170/0x2c0
�<0000000000199d9e>¨ online_store_recog_and_online+0x5a/0x14c
�<000000000019a08a>¨ online_store+0xbe/0x2ec
�<000000000018456c>¨ dev_attr_store+0x38/0x58
�<000000000010efbc>¨ sysfs_write_file+0x130/0x190
�<00000000000af582>¨ vfs_write+0xb2/0x160
�<00000000000afc7c>¨ sys_write+0x54/0x9c
�<0000000000025e16>¨ sys32_write+0x2e/0x50
�<0000000000024218>¨ sysc_noemu+0x10/0x16
�<0000000077e82bd2>¨ 0x77e82bd2
INFO: lockdep is turned off.
Josef 'Jeff' Sipek.
--
Research, n.:
Consider Columbus:
He didn't know where he was going.
When he got there he didn't know where he was.
When he got back he didn't know where he had been.
And he did it all on someone else's money.
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