(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface). On Tue, 27 Sep 2016 17:57:08 +0000 bugzilla-daemon@xxxxxxxxxxxxxxxxxxx wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=172981 > > Bug ID: 172981 > Summary: [bisected] SLAB: extreme load averages and over 2000 > kworker threads > Product: Memory Management > Version: 2.5 > Kernel Version: 4.7+ > Hardware: All > OS: Linux > Tree: Mainline > Status: NEW > Severity: normal > Priority: P1 > Component: Slab Allocator > Assignee: akpm@xxxxxxxxxxxxxxxxxxxx > Reporter: dsmythies@xxxxxxxxx > Regression: No > > Immediately after boot, extreme load average numbers and over 2000 kworker > processes are being observed on my main linux test computer (basically a Ubuntu > 16.04 server, no GUI). The worker threads appear to be idle, and do disappear > after the nominal 5 minute timeout, depending on whatever other stuff might run > in the meantime. However, the number of threads can hugely increase again. The > issue occurs with ease for kernels compiled using SLAB. > > For SLAB, kernel bisection gave: > 801faf0db8947e01877920e848a4d338dd7a99e7 > "mm/slab: lockless decision to grow cache" > > The following monitoring script was used for the below examples: > > #!/bin/dash > > while [ 1 ]; > do > echo $(uptime) ::: $(ps -A --no-headers | wc -l) ::: $(ps aux | grep kworker > | grep -v u | grep -v H | wc -l) > sleep 10.0 > done > > Example (SLAB): > > After boot: > > 22:26:21 up 1 min, 2 users, load average: 295.98, 85.67, 29.47 ::: 2240 ::: > 2074 > 22:26:31 up 1 min, 2 users, load average: 250.47, 82.85, 29.15 ::: 2240 ::: > 2074 > 22:26:41 up 1 min, 2 users, load average: 211.96, 80.12, 28.84 ::: 2240 ::: > 2074 > ... > 22:52:34 up 27 min, 3 users, load average: 0.00, 0.43, 5.40 ::: 165 ::: 17 > 22:52:44 up 27 min, 3 users, load average: 0.00, 0.42, 5.34 ::: 165 ::: 17 > > Now type: sudo echo "bla": > > 22:53:14 up 27 min, 3 users, load average: 0.00, 0.38, 5.17 ::: 493 ::: 345 > 22:53:24 up 28 min, 3 users, load average: 0.00, 0.36, 5.11 ::: 493 ::: 345 > > Caused 328 new kworker threads. > Now queue just a few (8 in this case) very simple jobs. > > 22:55:45 up 30 min, 3 users, load average: 0.11, 0.27, 4.38 ::: 493 ::: 345 > 22:55:55 up 30 min, 3 users, load average: 0.09, 0.26, 4.34 ::: 2207 ::: 2059 > 22:56:05 up 30 min, 3 users, load average: 0.08, 0.25, 4.29 ::: 2207 ::: 2059 > > If I look at linux/Documentation/workqueue.txt and do: > > echo workqueue:workqueue_queue_work > /sys/kernel/debug/tracing/set_event > > and: > > cat /sys/kernel/debug/tracing/trace_pipe > out.txt > > I get somewhere between 10,000 and 20,000 occurrences of > memcg_kmem_cache_create_func in the file (using my simple test method). > > Also tested with kernel 4.8-rc7. > > -- > You are receiving this mail because: > You are the assignee for the bug. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>