These hangs happen during random I/O fio benchmark loads. Something
like 4 or 8 fio processes doing random reads/writes to distinct large
files (to ensure there is no caching possible). This is all on CentOS
7.4 nodes. Same (and even tougher) tests run without any problems with
ceph-fuse. We do have jobs that do heavy parallel I/O (MPI-IO, HDF5 via
MPI-IO, etc.) - so running 8 parallel random I/O generating processes on
nodes with 28 cores and plenty of RAM (256GB - 512GB) should not be
excessive.
I am going to test the latest CentOS kernel next (the one you are
referencing). The RedHat/CentOS kernels are not "old kernel clients" -
they contains various backports of hundreds of patches to all kinds of
subsystems of Linux. What is unclear there is exactly what ceph client
RedHat is backporting to their kernels. Any pointers there would be
helpful.
Andras
On 10/1/18 2:26 PM, Marc Roos wrote:
How do you test this? I have had no issues under "normal load" with an
old kernel client and a stable os.
CentOS Linux release 7.5.1804 (Core)
Linux c04 3.10.0-862.11.6.el7.x86_64 #1 SMP Tue Aug 14 21:49:04 UTC 2018
x86_64 x86_64 x86_64 GNU/Linux
-----Original Message-----
From: Andras Pataki [mailto:apataki@xxxxxxxxxxxxxxxxxxxxx]
Sent: maandag 1 oktober 2018 20:10
To: ceph-users
Subject: cephfs kernel client stability
We have so far been using ceph-fuse for mounting cephfs, but the small
file performance of ceph-fuse is often problematic. We've been testing
the kernel client, and have seen some pretty bad crashes/hangs.
What is the policy on fixes to the kernel client? Is only the latest
stable kernel updated (4.18.x nowadays), or are fixes backported to LTS
kernels also (like 4.14.x or 4.9.x for example)? I've seen various
threads that certain newer features require pretty new kernels - but I'm
wondering whether newer kernels are also required for better stability -
or - in general, where the kernel client stability stands nowadays.
Here is an example of kernel hang with 4.14.67. On heavy loads the
machine isn't even pingable.
Sep 29 21:10:16 worker1004 kernel: INFO: rcu_sched self-detected stall
on CPU Sep 29 21:10:16 worker1004 kernel: #0111-...: (1 GPs behind)
idle=bee/140000000000001/0 softirq=21319/21319 fqs=7499 Sep 29 21:10:16
worker1004 kernel: #011 (t=15000 jiffies g=13989 c=13988
q=8334)
Sep 29 21:10:16 worker1004 kernel: NMI backtrace for cpu 1 Sep 29
21:10:16 worker1004 kernel: CPU: 1 PID: 19436 Comm: kworker/1:42
Tainted: P W O 4.14.67 #1
Sep 29 21:10:16 worker1004 kernel: Hardware name: Dell Inc. PowerEdge
C6320/082F9M, BIOS 2.6.0 10/27/2017 Sep 29 21:10:16 worker1004 kernel:
Workqueue: ceph-msgr ceph_con_workfn [libceph] Sep 29 21:10:16
worker1004 kernel: Call Trace:
Sep 29 21:10:16 worker1004 kernel: <IRQ> Sep 29 21:10:16 worker1004
kernel: dump_stack+0x46/0x5f Sep 29 21:10:16 worker1004 kernel:
nmi_cpu_backtrace+0xba/0xc0 Sep 29 21:10:16 worker1004 kernel: ?
irq_force_complete_move+0xd0/0xd0 Sep 29 21:10:16 worker1004 kernel:
nmi_trigger_cpumask_backtrace+0x8a/0xc0
Sep 29 21:10:16 worker1004 kernel: rcu_dump_cpu_stacks+0x81/0xb1 Sep 29
21:10:16 worker1004 kernel: rcu_check_callbacks+0x642/0x790 Sep 29
21:10:16 worker1004 kernel: ? update_wall_time+0x26d/0x6e0 Sep 29
21:10:16 worker1004 kernel: update_process_times+0x23/0x50 Sep 29
21:10:16 worker1004 kernel: tick_sched_timer+0x2f/0x60 Sep 29 21:10:16
worker1004 kernel: __hrtimer_run_queues+0xa3/0xf0 Sep 29 21:10:16
worker1004 kernel: hrtimer_interrupt+0x94/0x170 Sep 29 21:10:16
worker1004 kernel: smp_apic_timer_interrupt+0x4c/0x90
Sep 29 21:10:16 worker1004 kernel: apic_timer_interrupt+0x84/0x90 Sep 29
21:10:16 worker1004 kernel: </IRQ> Sep 29 21:10:16 worker1004 kernel:
RIP: 0010:crush_hash32_3+0x1e5/0x270 [libceph] Sep 29 21:10:16
worker1004 kernel: RSP: 0018:ffffc9000fdff5d8 EFLAGS:
00000a97 ORIG_RAX: ffffffffffffff10
Sep 29 21:10:16 worker1004 kernel: RAX: 0000000006962033 RBX:
ffff883f6e7173c0 RCX: 00000000dcdcc373
Sep 29 21:10:16 worker1004 kernel: RDX: 00000000bd5425ca RSI:
000000008a8b0b56 RDI: 00000000b1983b87
Sep 29 21:10:16 worker1004 kernel: RBP: 0000000000000023 R08:
00000000bd5425ca R09: 00000000137904e9
Sep 29 21:10:16 worker1004 kernel: R10: 0000000000000000 R11:
0000000000000002 R12: 00000000b0f29f21
Sep 29 21:10:16 worker1004 kernel: R13: 000000000000000c R14:
00000000f0ae0000 R15: 0000000000000023
Sep 29 21:10:16 worker1004 kernel: crush_bucket_choose+0x2ad/0x340
[libceph] Sep 29 21:10:16 worker1004 kernel:
crush_choose_firstn+0x1b0/0x4c0 [libceph] Sep 29 21:10:16 worker1004
kernel: crush_choose_firstn+0x48d/0x4c0 [libceph] Sep 29 21:10:16
worker1004 kernel: crush_do_rule+0x28c/0x5a0 [libceph] Sep 29 21:10:16
worker1004 kernel: ceph_pg_to_up_acting_osds+0x459/0x850
[libceph]
Sep 29 21:10:16 worker1004 kernel: calc_target+0x213/0x520 [libceph] Sep
29 21:10:16 worker1004 kernel: ? ixgbe_xmit_frame_ring+0x362/0xe80
[ixgbe] Sep 29 21:10:16 worker1004 kernel: ? put_prev_entity+0x27/0x620
Sep 29 21:10:16 worker1004 kernel: ? pick_next_task_fair+0x1c7/0x520 Sep
29 21:10:16 worker1004 kernel:
scan_requests.constprop.55+0x16f/0x280 [libceph] Sep 29 21:10:16
worker1004 kernel: handle_one_map+0x175/0x200 [libceph] Sep 29 21:10:16
worker1004 kernel: ceph_osdc_handle_map+0x390/0x850 [libceph] Sep 29
21:10:16 worker1004 kernel: ? ceph_x_encrypt+0x46/0x70 [libceph] Sep 29
21:10:16 worker1004 kernel: dispatch+0x2ef/0xba0 [libceph] Sep 29
21:10:16 worker1004 kernel: ? read_partial_message+0x215/0x880 [libceph]
Sep 29 21:10:16 worker1004 kernel: ? inet_recvmsg+0x45/0xb0 Sep 29
21:10:16 worker1004 kernel: try_read+0x6f8/0x11b0 [libceph] Sep 29
21:10:16 worker1004 kernel: ? sched_clock_cpu+0xc/0xa0 Sep 29 21:10:16
worker1004 kernel: ? put_prev_entity+0x27/0x620 Sep 29 21:10:16
worker1004 kernel: ? pick_next_task_fair+0x415/0x520 Sep 29 21:10:16
worker1004 kernel: ceph_con_workfn+0x9d/0x5a0 [libceph] Sep 29 21:10:16
worker1004 kernel: process_one_work+0x127/0x290 Sep 29 21:10:16
worker1004 kernel: worker_thread+0x3f/0x3b0 Sep 29 21:10:16 worker1004
kernel: kthread+0xf2/0x130 Sep 29 21:10:16 worker1004 kernel: ?
process_one_work+0x290/0x290 Sep 29 21:10:16 worker1004 kernel: ?
__kthread_parkme+0x90/0x90 Sep 29 21:10:16 worker1004 kernel:
ret_from_fork+0x1f/0x30
Andras
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