On 16.01.21 22:46, Vladimir Sementsov-Ogievskiy wrote:
Hi Max!
I applied my series onto yours 129-fixing and found, that 129 fails for backup.
And setting small max-chunk and even max-workers to 1 doesn't help! (setting
speed like in v3 still helps).
And I found, that the problem is that really, the whole backup job goes during
drain, because in new architecture we do just job_yield() during the whole
background block-copy.
This leads to modifying the existing patch in the series, which does job_enter()
from job_user_pause: we just need call job_enter() from job_pause() to cover
not only user pauses but also drained_begin.
So, now I don't need any additional fixing of 129.
Changes in v4:
- add a lot of Max's r-b's, thanks!
03: fix over-80 line (in comment), add r-b
09: was "[PATCH v3 10/25] job: call job_enter from job_user_pause",
now changed to finally fix 129 iotest, drop r-b
10: squash-in additional wording on max-chunk, fix error message, keep r-b
17: drop extra include, assert job_is_cancelled() instead of check, add r-b
18: adjust commit message, add r-b
23: add comments and assertion, about the fact that test doesn't support
paths with colon inside
fix s/disable-copy-range/use-copy-range/
Hmmm, for me, 129 sometimes fails still, because it completes too quickly...
(The error then is that 'return[0]' does not exist in query-block-jobs’s
result, because the job is already gone.)
When I insert a print(result) after the query-block-jobs, I can see that the
job has always progressed really far, even if its still running. (Like,
generally the offset is just one MB shy of 1G.)
I suspect the problem is that block-copy just copies too much from the start
(by default); i.e., it starts 64 workers with, hm, well, 1 MB of chunk size?
Shouldn’t fill the 128 MB immediately...
Anyway, limiting the number of workers (to 1) and the chunk size (to 64k) with
x-perf does ensure that the backup job’s progress is limited to 1 MB or so,
which looks fine to me.
I suppose we should do that, then (in 129), before patch 17?