Re: [Xen-devel] poor domU VBD performance.

[Andrew Theurer <habanero@xxxxxxxxxx>]

> Could you try again, but replace calls to
> blk_run_queue(plugged_queue) in blkback.c with:
>     if ( plugged_queue->unplug_fn )
>            plugged_queue->unplug_fn(plugged_queue);
>
> This looks like a better match with what various other drivers do
> (e.g. swraid).

Sorry, It looks like did not get you the whole output, but I can try 
what you suggested.

Unable to handle kernel NULL pointer dereference at virtual address 
00000000
 printing eip:
00000000
*pde = ma 00000000 pa 55555000
 [<c02691f1>] blkio_schedule+0x126/0x14c
 [<c01147b5>] default_wake_function+0x0/0x12
 [<c01147b5>] default_wake_function+0x0/0x12
 [<c02690cb>] blkio_schedule+0x0/0x14c
 [<c01071f1>] kernel_thread_helper+0x5/0xb
Oops: 0000 [#1]
Modules linked in: ipt_MASQUERADE iptable_nat ip_conntrack ip_tables 
qla2300 qla2xxx scsi_transport_fc mptscsih mptbase
CPU:    0
EIP:    0061:[<00000000>]    Not tainted VLI
EFLAGS: 00010282   (2.6.11-xen0-up)
EIP is at 0x0
eax: 00000000   ebx: f5ec9b70   ecx: f3e13b64   edx: 00000000
esi: 00000000   edi: c044540c   ebp: f7d8dfc0   esp: f7d8df84
ds: 007b   es: 007b   ss: 0069
Process xenblkd (pid: 730, threadinfo=f7d8c000 task=f7d43020)
Stack: c0217f7d f5ec9b70 f3fee6f0 f7d8c000 c02691f1 f5ec9b70 00000010 
00000000
       f7d43020 c01147b5 00000000 00000000 fbffc000 00000000 f7d8c000 
00000000
       f7d43020 c01147b5 00100100 00200200 00000000 00000000 00000000 
c02690cb
Call Trace:
 [<c0217f7d>] blk_run_queue+0x24/0x47
 [<c02691f1>] blkio_schedule+0x126/0x14c
 [<c01147b5>] default_wake_function+0x0/0x12
 [<c01147b5>] default_wake_function+0x0/0x12
 [<c02690cb>] blkio_schedule+0x0/0x14c
 [<c01071f1>] kernel_thread_helper+0x5/0xb
Code:  Bad EIP value.

>
>   Thanks,
>   Keir


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