I noticed that blktests block/004 takes longer runtime with 5.6-rc4 than
5.6-rc3, and found that the commit 01e99aeca397 ("blk-mq: insert passthrough
request into hctx->dispatch directly") triggers it.
The longer runtime was observed with dm-linear device which maps SATA SMR HDD
connected via AHCI. It was not observed with dm-linear on SAS/SATA SMR HDDs
connected via SAS-HBA. Not observed with dm-linear on non-SMR HDDs either.
Before the commit, block/004 took around 130 seconds. After the commit, it takes
around 300 seconds. I need to dig in further details to understand why the
commit makes the test case longer.
The test case block/004 does "flush intensive workload". Is this longer runtime
expected?
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Best Regards,
Shin'ichiro Kawasaki
