Comment 0 for bug 1855409

This bug is similar to #1832082 (bnx2x driver causes 100% CPU load) but applies for qede driver instead of bnx2x. The symptoms are the same:

With chrony installed, and configured with "hwtimestamp *", I observe 100% CPU load on 2 CPU cores.

Running perf report shows that kernel is busy executing qede_ptp_task function in qede driver.

A workaround is to disable "hwtimestamp *" in chrony configuration.

---

$ modinfo qede
filename: /lib/modules/4.15.0-72-generic/kernel/drivers/net/ethernet/qlogic/qede/qede.ko
version: 8.10.10.21
license: GPL
description: QLogic FastLinQ 4xxxx Ethernet Driver
srcversion: D5EC89D815FC81B973EE9F0
alias: pci:v00001077d00008090sv*sd*bc*sc*i*
alias: pci:v00001077d00008070sv*sd*bc*sc*i*
alias: pci:v00001077d00001664sv*sd*bc*sc*i*
alias: pci:v00001077d00001656sv*sd*bc*sc*i*
alias: pci:v00001077d00001654sv*sd*bc*sc*i*
alias: pci:v00001077d00001644sv*sd*bc*sc*i*
alias: pci:v00001077d00001636sv*sd*bc*sc*i*
alias: pci:v00001077d00001666sv*sd*bc*sc*i*
alias: pci:v00001077d00001634sv*sd*bc*sc*i*
depends: ptp,qed
retpoline: Y
intree: Y
name: qede
vermagic: 4.15.0-72-generic SMP mod_unload
signat: PKCS#7
signer:
sig_key:
sig_hashalgo: md4
parm: debug: Default debug msglevel (uint)

$ uname -a
Linux dcn1-clm-inf-1 4.15.0-72-generic #81-Ubuntu SMP Tue Nov 26 12:20:02 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

$ lspci | grep -i ether
19:00.0 Ethernet controller: QLogic Corp. FastLinQ QL41000 Series 10/25/40/50GbE Controller (rev 02)
19:00.1 Ethernet controller: QLogic Corp. FastLinQ QL41000 Series 10/25/40/50GbE Controller (rev 02)
19:00.2 Ethernet controller: QLogic Corp. FastLinQ QL41000 Series 10/25/40/50GbE Controller (rev 02)
19:00.3 Ethernet controller: QLogic Corp. FastLinQ QL41000 Series 10/25/40/50GbE Controller (rev 02)

# perf report snippet:

  Children Self Command Shared Object
- 44.76% 0.00% kworker/16:5 [kernel.kallsyms]
     ret_from_fork
   - kthread
      - 44.74% worker_thread
         - 44.57% process_one_work
            - 42.67% qede_ptp_task
               - 38.86% qed_ptp_hw_read_tx_ts
                    qed_rd
               - 3.03% queue_work_on
                  - 2.06% __queue_work
                     - 0.68% get_work_pool
                        - 0.61% radix_tree_lookup
                             __radix_tree_lookup
              0.50% set_work_pool_and_clear_pending