Oracle Linux: iSCSI Devices Hang on "rq_qos_wait " System Call
(Doc ID 2769797.1)
Last updated on AUGUST 26, 2021
Applies to:
Oracle Cloud Infrastructure - Version N/A and laterLinux OS - Version Oracle Linux 7.0 and later
Information in this document applies to any platform.
Symptoms
Under heavy IO, iSCSI block volumes hang.
Checking the system call stack of the hang processes they frequently stay in "rq_qos_wait"
$ sudo ps -eo pid,stat,wchan:30,comm | grep D
PID STAT WCHAN COMMAND
2570 D wait_on_page_bit dd
5514 D rq_qos_wait kworker/u64:1+f
7115 D+ xfs_ilock ls
12596 D+ xfs_ilock ls
14067 D+ rq_qos_wait vim
16030 D rq_qos_wait kworker/0:1+xfs
16982 D xfs_ilock ls
22192 D+ balance_dirty_pages dd
25037 D rwsem_down_write_slowpath xfs_io
25269 D xfs_ilock ls
26291 D rq_qos_wait dd
26602 D rwsem_down_write_slowpath chmod
27215 D rwsem_down_write_slowpath xfs_io
29329 D wb_wait_for_completion sync
29999 D rq_qos_wait dd
31573 D+ rq_qos_wait dd
Changes
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |