On 1/21/19 1:01 PM, Florian Stecker wrote:
on my laptop, I am experiencing occasional hangs of applications during
fsync(), which are sometimes up to 30 seconds long. I'm using a BTRFS
which spans two partitions on the same SSD (one of them used to contain
a Windows, but I removed it and added the partition to the BTRFS volume
instead). Also, the problem only occurs when an I/O scheduler
(mq-deadline) is in use. I'm running kernel version 4.20.3.
From what I understand so far, what happens is that a sync request
fails in the SCSI/ATA layer, in ata_std_qc_defer(), because it is a
"Non-NCQ command" and can not be queued together with other commands.
This propagates up into blk_mq_dispatch_rq_list(), where the call
Can you have a look at
https://bugzilla.kernel.org/show_bug.cgi?id=202353 and see whether that
issue is related to what you encountered?
Thanks,
Bart.
