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Re: [PATCH v4 00/23] backup performance: block_status + async


From: Vladimir Sementsov-Ogievskiy
Subject: Re: [PATCH v4 00/23] backup performance: block_status + async
Date: Tue, 19 Jan 2021 22:29:24 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1

19.01.2021 22:22, Vladimir Sementsov-Ogievskiy wrote:
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?

Yes, that sounds reasonable

Still, may be keeping number of workers >1 is good to, to test new 
architecture.. Just make it to be 4 or 8

--
Best regards,
Vladimir



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