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Re: [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of rac
From: |
Sascha Silbe |
Subject: |
Re: [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of race condition on systems with fast IO |
Date: |
Thu, 07 Apr 2016 22:27:55 +0200 |
User-agent: |
Notmuch/0.19+1~g6b3e223 (http://notmuchmail.org) Emacs/24.3.1 (x86_64-pc-linux-gnu) |
Dear Max,
Max Reitz <address@hidden> writes:
> On 05.04.2016 11:21, Sascha Silbe wrote:
>> On systems with fast IO, qemu-io may write more than 1 MiB before
>> receiving the block-job-cancel command, causing the test case to fail.
>>
>> 141 is inherently racy, but we can at least reduce the likelihood of the
>> job completing before the cancel command arrives by bumping the size of
>> the data getting written; we'll try 32 MiB for a start.
>
> Hm, interesting. I tried to prevent this by setting the block jobs'
> speed to 1, which should make it stop after the block job has processed
> the first block of data.
Hmm, seems like I didn't quite understand the way the test works
then.
@Kevin: Please do NOT queue this patch.
@Max: From a cursory glance at the code, maybe your 1 *byte* per second
rate limit is being rounded down to 0 *blocks* per second, with 0
meaning no limit? See e.g. mirror_set_speed(). Though I must admit I
don't understand how speed=0 translates to unlimited (like
qapi/block-core.json:block-job-set-speed says). My understanding of
ratelimit_calculate_delay() is that speed=0 means "1 quantum per time
slice", with time slice usually being 100ms; not sure about the
quantum.
Sascha
--
Softwareentwicklung Sascha Silbe, Niederhofenstraße 5/1, 71229 Leonberg
https://se-silbe.de/
USt-IdNr. DE281696641
- Re: [Qemu-block] [PATCH 2/7] qemu-iotests: fix 051 on non-PC architectures, (continued)
- [Qemu-block] [PATCH 3/7] qemu-iotests: iotests.VM: remove qtest socket on error, Sascha Silbe, 2016/04/05
- [Qemu-block] [PATCH 1/7] qemu-iotests: check: don't place files with predictable names in /tmp, Sascha Silbe, 2016/04/05
- [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of race condition on systems with fast IO, Sascha Silbe, 2016/04/05
- Re: [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of race condition on systems with fast IO, Max Reitz, 2016/04/06
- Re: [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of race condition on systems with fast IO, Kevin Wolf, 2016/04/06
- Re: [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of race condition on systems with fast IO,
Sascha Silbe <=
- Re: [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of race condition on systems with fast IO, Kevin Wolf, 2016/04/08
- Re: [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of race condition on systems with fast IO, Sascha Silbe, 2016/04/08
- Re: [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of race condition on systems with fast IO, Kevin Wolf, 2016/04/08
- Re: [Qemu-block] [PATCH 6/7] qemu-iotests: 141: reduce likelihood of race condition on systems with fast IO, Sascha Silbe, 2016/04/08
[Qemu-block] [PATCH 4/7] qemu-iotests: 148: properly skip test if quorum support is missing, Sascha Silbe, 2016/04/05
Re: [Qemu-block] [PATCH 0/7] next round of qemu-iotests fixes, Max Reitz, 2016/04/08