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Boaz Harrosh | 9 Feb 2011 20:02
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Regression with calibrate_xor_blocks, probably UML related

I have a new module that uses the async_tx.h lib.

On an exact same module code based on 3.6.37 I see the:
	xor: measuring software checksum speed
	   8regs     : 11312.000 MB/sec
	   8regs_prefetch:  9792.800 MB/sec
	   32regs    : 11220.400 MB/sec
	   32regs_prefetch:  9750.800 MB/sec
	xor: using function: 8regs (11312.000 MB/sec)

And all is well. But on code based on 2.6.38-rc4 I get hard stuck
right after:
	xor: measuring software checksum speed

the UML is completely frozen. When I kill the uml from the host
I can sometimes get this trace.

750c7498:  [<6005f936>] bad_page+0xd8/0xf3
750c74c8:  [<60060c93>] get_page_from_freelist+0x333/0x47b
750c7508:  [<60131243>] put_dec+0x20/0x3c
750c75a0:  [<6001a0ac>] change_pre_exec+0x0/0x24
750c75b8:  [<60060ef1>] __alloc_pages_nodemask+0x116/0x65b
750c7668:  [<60132e25>] sprintf+0xa1/0xa3
750c76a0:  [<6001a0ac>] change_pre_exec+0x0/0x24
750c76b8:  [<60061446>] __get_free_pages+0x10/0x43
750c76c8:  [<60012875>] alloc_stack+0x1b/0x1d
750c76d8:  [<6001fe27>] run_helper+0x26/0x1b5
750c76e8:  [<60021553>] set_signals+0x1c/0x2e
750c7708:  [<6007efac>] __kmalloc+0x9e/0xc4
750c7748:  [<6001a544>] change+0x124/0x189
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Boaz Harrosh | 10 Feb 2011 16:51
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Re: Regression with calibrate_xor_blocks, probably UML related

On 02/09/2011 09:02 PM, Boaz Harrosh wrote:
> I have a new module that uses the async_tx.h lib.
> 
> On an exact same module code based on 3.6.37 I see the:
> 	xor: measuring software checksum speed
> 	   8regs     : 11312.000 MB/sec
> 	   8regs_prefetch:  9792.800 MB/sec
> 	   32regs    : 11220.400 MB/sec
> 	   32regs_prefetch:  9750.800 MB/sec
> 	xor: using function: 8regs (11312.000 MB/sec)
> 
> And all is well. But on code based on 2.6.38-rc4 I get hard stuck
> right after:
> 	xor: measuring software checksum speed
> 

OK this is not dependent on Kernel version it is the same for both
.38-rc4 and .37. I was just lucky with .37 more.

And the same things happen with raid456 module. I do
[]$ modprobe raid456; modprobe --remove raid456
A few times it loads, printing the above checks, Then At one
time it freezes. Sometimes at first attempt sometimes at 4-7
attempts. I never went 10 times strait.

When it freezes (hard) I can see in my host that the UML is
at 100% CPU.

BTW: when I manage to pass the tests I get the above numbers
But when I load directly on the host I get:
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