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Re: [Qemu-block] [PATCH v4] iotests: Tweak 030 in order to trigger a rac

From: Max Reitz
Subject: Re: [Qemu-block] [PATCH v4] iotests: Tweak 030 in order to trigger a race condition with parallel jobs
Date: Wed, 7 Mar 2018 18:54:51 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0

On 2018-03-06 14:01, 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 awakened it will finish right
> away without any chance of being stopped by block_job_sleep_ns(). This
> triggers the bug that was fixed by 3d5d319e1221082974711af1d09d82f and
> 1a63a907507fbbcfaee3f622907ec24 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.
> Since with this change the stream job in test_stream_commit() finishes
> early, this patch introduces a similar test case where both jobs are
> slowed down so they can actually run in parallel.
> Signed-off-by: Alberto Garcia <address@hidden>
> Cc: John Snow <address@hidden>
> ---
> v4: Mention that commit 1a63a907507fbbcfaee3f622907ec24 also
>     contributes to solve the original bug (both commits need to
>     reverted in order to reproduce this bug reliably).
>     Rewrite the loop that writes data into the images to make it more
>     readable.

Thanks!  Applied to my block tree:


(Still took me a couple of attempts to get it to fail both commits
reverted, though...)


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