Re: [Qemu-devel] [PATCH] iotests: Tweak 030 in order to trigger a race condition with parallel jobs

[Eric Blake <eblake@redhat.com>]

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On 12/07/2017 11:08 AM, Alberto Garcia wrote:
> This patch tweaks TestParallelOps in iotest 030 so it allocates data
> in smaller regions (256KB/512KB instead of 512KB/1MB) and the
> block-stream job in test_stream_commit() only needs to copy data that
> is at the very end of the image.
> 
> This way when the block-stream job is waken up it will finish right

s/waken up/awakened/

> away without any chance of being stopped by block_job_sleep_ns(). This
> triggers the bug that was fixed by 3d5d319e1221082974711af1d09d82f07
> and is therefore a more useful test case for parallel block jobs.
> 
> After this patch the aforementiond bug can also be reproduced with the
> test_stream_parallel() test case.
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>  tests/qemu-iotests/030 | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 

>          # Put data into the images we are copying data from
>          for i in range(self.num_imgs / 2):
> -            img_index = i * 2 + 1
> -            # Alternate between 512k and 1M.
> +            img_index = self.num_imgs - i * 2 - 2
> +            # Alternate between 256KB and 512KB.
>              # This way jobs will not finish in the same order they were created
> -            num_kb = 512 + 512 * (i % 2)
> +            num_kb = 256 + 256 * (i % 2)
>              qemu_io('-f', iotests.imgfmt,
> -                    '-c', 'write -P %d %d %d' % (i, i*1024*1024, num_kb * 1024),
> +                    '-c', 'write -P 0xFF %dk %dk' % (i * 512, num_kb),

I guess changing from a variable to a fixed 0xff pattern doesn't make a
difference?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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