Here are gdb oupout with librbd1-dbg and librados2-dbg. --------------------------------------------------------- [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". 0x00007ff8cf8dddff in ppoll () from /lib/x86_64-linux-gnu/libc.so.6
Thread 522 (Thread 0x7ff8ccb56700 (LWP 4959)): #0 0x00007ff8cf8e2809 in syscall () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x00007ff8cf198012 in ?? () from /usr/lib/x86_64-linux-gnu/liblttng-ust.so.0 #2 0x00007ff8cfbb10a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #3 0x00007ff8cf8e687d in clone () from /lib/x86_64-linux-gnu/libc.so.6 Thread 521 (Thread 0x7ff8cc355700 (LWP 4960)): #0 0x00007ff8cf8e2809 in syscall () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x00007ff8cf198012 in ?? () from /usr/lib/x86_64-linux-gnu/liblttng-ust.so.0 #2 0x00007ff8cfbb10a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #3 0x00007ff8cf8e687d in clone () from /lib/x86_64-linux-gnu/libc.so.6 Thread 520 (Thread 0x7ff8cbb54700 (LWP 4961)): #0 0x00007ff8cf8e2809 in syscall () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x0000000000833d00 in futex_wait (ev=0x1222e04 <rcu_call_ready_event>, val=4294967295) at util/qemu-thread-posix.c:292 #2 0x0000000000833e8e in qemu_event_wait (ev=0x1222e04 <rcu_call_ready_event>) at util/qemu-thread-posix.c:399 #3 0x0000000000849382 in call_rcu_thread (opaque=0x0) at util/rcu.c:250 #4 0x00007ff8cfbb10a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #5 0x00007ff8cf8e687d in clone () from /lib/x86_64-linux-gnu/libc.so.6 Thread 519 (Thread 0x7ff8cab1c700 (LWP 4974)): #0 0x00007ff8cfbb508f in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007ff8d17a563b in ceph::log::Log::entry (this=0x1643a60) at log/Log.cc:353 #2 0x00007ff8cfbb10a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #3 0x00007ff8cf8e687d in clone () from /lib/x86_64-linux-gnu/libc.so.6 Thread 518 (Thread 0x7ff8c9b8d700 (LWP 4975)): #0 0x00007ff8cfbb5438 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007ff8d1535acb in WaitUntil (when=..., mutex=..., this=0x1692bd8) at ./common/Cond.h:71 #2 WaitInterval (interval=..., mutex=..., cct=<optimized out>, this=0x1692bd8) at ./common/Cond.h:79 #3 CephContextServiceThread::entry (this=0x1692b60) at common/ceph_context.cc:96 #4 0x00007ff8cfbb10a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #5 0x00007ff8cf8e687d in clone () from /lib/x86_64-linux-gnu/libc.so.6 Thread 517 (Thread 0x7ff8c938c700 (LWP 4976)): #0 0x00007ff8cfbb5438 in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007ff8d15125c1 in WaitUntil (when=..., mutex=..., this=0x1694978) at common/Cond.h:71 #2 SafeTimer::timer_thread (this=0x1694968) at common/Timer.cc:118 #3 0x00007ff8d1512efd in SafeTimerThread::entry (this=<optimized out>) at common/Timer.cc:38 #4 0x00007ff8cfbb10a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #5 0x00007ff8cf8e687d in clone () from /lib/x86_64-linux-gnu/libc.so.6 Thread 516 (Thread 0x7ff8c8b8b700 (LWP 4977)): #0 0x00007ff8cfbb508f in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007ff8d1696b70 in Wait (mutex=..., this=0x1693f50) at ./common/Cond.h:55 #2 DispatchQueue::entry (this=0x1693ee8) at msg/simple/DispatchQueue.cc:196 #3 0x00007ff8d16c65fd in DispatchQueue::DispatchThread::entry (this=<optimized out>) at msg/simple/DispatchQueue.h:103 #4 0x00007ff8cfbb10a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #5 0x00007ff8cf8e687d in clone () from /lib/x86_64-linux-gnu/libc.so.6 Thread 515 (Thread 0x7ff8c838a700 (LWP 4978)): #0 0x00007ff8cfbb508f in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007ff8d1699ba6 in Wait (mutex=..., this=0x16940f0) at ./common/Cond.h:55 #2 DispatchQueue::run_local_delivery (this=0x1693ee8) at msg/simple/DispatchQueue.cc:114 #3 0x00007ff8d16c66dd in DispatchQueue::LocalDeliveryThread::entry (this=<optimized out>) at msg/simple/DispatchQueue.h:117 #4 0x00007ff8cfbb10a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #5 0x00007ff8cf8e687d in clone () from /lib/x86_64-linux-gnu/libc.so.6 Thread 514 (Thread 0x7ff8c7b89700 (LWP 4979)): #0 0x00007ff8cfbb508f in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007ff8d16bde99 in Wait (mutex=..., this=0x1694358) at ./common/Cond.h:55 #2 SimpleMessenger::reaper_entry (this=0x1693d20) at msg/simple/SimpleMessenger.cc:211 #3 0x00007ff8d16c6cdd in SimpleMessenger::ReaperThread::entry (this=<optimized out>) at msg/simple/SimpleMessenger.h:195 #4 0x00007ff8cfbb10a4 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #5 0x00007ff8cf8e687d in clone () from /lib/x86_64-linux-gnu/libc.so.6 ........ ........ ........ (all the log in attachment: debug.log) --------------------------------------------------------------------------- ** Attachment added: "gdb thread apply all bt with librbd1-dbg and librados2-dbg" https://bugs.launchpad.net/qemu/+bug/1581334/+attachment/4662277/+files/debug.log -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1581334 Title: qemu + librbd takes high %sy cpu under high random io workload Status in Ceph: New Status in Linux: New Status in QEMU: New Bug description: I got an IO problem. When running Qemu + ceph(use librbd), and do a random IO benchmark or some high load random IO test, it will exhaust all my host cpu on %sy cpu. It doesn’t happen all the time, but when it appear it will reproduce every time I start a random IO benchmark(test with Fio). And the only way to fix the problem is shutdown my vm and start it, but the problem will happen again with high random IO load. Some information: Vendor : HP Product : HP ProLiant BL460c Gen9 Kernel : 3.16.0-4-amd64 Disto : Debian Version : 8.4 Arch : amd64 Qemu : 2.1 ~ 2.6 (Yes, I already test the latest qemu2.6 version, but still got the problem) Ceph : Hammer 0.94.5 Librbd : 0.94.5 ~ 10.2 (I rebuild librbd with ceph 10.2 source code, but the problem still here) Qemu config : cache=none Qemu cpu&mem: 4core, 8GB How can i reproduce the problem? while :; do bash randwrite.sh ; sleep 3600; done >test.log 2>&1 & (Sleep 3600 is the key to reproduce my problem. I don’t known how long sleep suit for reproduce, but one hour sleep is enough. the problem will easy reproduce after a long sleep, if i keep benchmark running without sleep, i can't reproduce it) My randwrite.sh script ---------------------------------------------- #!/bin/sh sync echo 3 > /proc/sys/vm/drop_caches FILENAME=/dev/vdc RUNTIME=100 BLOCKSIZE=4K IOENGINE=libaio RESULTFILE=fio-randwrite.log IODEPTH=32 RAMP_TIME=5 SIZE=100G fio --numjobs 10 --norandommap --randrepeat=0 --readwrite=randwrite --ramp_time=$RAMP_TIME --bs=$BLOCKSIZE --runtime=$RUNTIME --iodepth=$IODEPTH --filename=$FILENAME --ioengine=$IOENGINE --direct=1 --name=iops_randwrite --group_reporting | tee $RESULTFILE ---------------------------------------------- What happened after the problem appear? my vm will got huge IOPS drop. In my case, it will drop from 15000 IOPS to 3500 IOPS. And other thing, my host cpu will exhaust on %sy. Top output like this. Qemu Fio benchmark ---------------------------------------------------- Tasks: 284 total, 2 running, 282 sleeping, 0 stopped, 0 zombie %Cpu0 : 11.8 us, 66.7 sy, 0.0 ni, 21.5 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu1 : 12.7 us, 64.9 sy, 0.0 ni, 22.4 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu2 : 13.7 us, 64.5 sy, 0.0 ni, 21.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu3 : 13.2 us, 64.1 sy, 0.0 ni, 22.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu4 : 11.7 us, 65.4 sy, 0.0 ni, 22.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu5 : 13.2 us, 64.4 sy, 0.0 ni, 22.4 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu6 : 12.4 us, 65.1 sy, 0.0 ni, 22.5 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu7 : 13.6 us, 63.8 sy, 0.0 ni, 22.6 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu8 : 9.8 us, 73.0 sy, 0.0 ni, 17.2 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu9 : 7.8 us, 74.5 sy, 0.0 ni, 17.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu10 : 6.0 us, 81.4 sy, 0.0 ni, 6.6 id, 0.0 wa, 0.0 hi, 6.0 si, 0.0 st %Cpu11 : 8.4 us, 79.5 sy, 0.0 ni, 8.8 id, 0.0 wa, 0.0 hi, 3.4 si, 0.0 st %Cpu12 : 7.6 us, 80.7 sy, 0.0 ni, 7.0 id, 0.0 wa, 0.0 hi, 4.7 si, 0.0 st %Cpu13 : 7.4 us, 79.9 sy, 0.0 ni, 7.7 id, 0.0 wa, 0.0 hi, 5.0 si, 0.0 st %Cpu14 : 9.8 us, 75.4 sy, 0.0 ni, 11.4 id, 0.0 wa, 0.0 hi, 3.4 si, 0.0 st %Cpu15 : 6.7 us, 80.1 sy, 0.0 ni, 10.1 id, 0.0 wa, 0.0 hi, 3.0 si, 0.0 st %Cpu16 : 9.2 us, 69.2 sy, 0.0 ni, 17.5 id, 0.0 wa, 0.0 hi, 4.1 si, 0.0 st %Cpu17 : 9.9 us, 66.6 sy, 0.0 ni, 20.1 id, 0.0 wa, 0.0 hi, 3.4 si, 0.0 st %Cpu18 : 16.6 us, 49.0 sy, 0.0 ni, 34.4 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu19 : 16.7 us, 46.4 sy, 0.0 ni, 36.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu20 : 13.0 us, 50.8 sy, 0.0 ni, 36.1 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu21 : 18.9 us, 46.2 sy, 0.0 ni, 34.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu22 : 12.1 us, 52.9 sy, 0.0 ni, 35.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu23 : 15.9 us, 47.6 sy, 0.0 ni, 36.6 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu24 : 6.7 us, 62.0 sy, 0.0 ni, 31.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu25 : 7.6 us, 63.7 sy, 0.0 ni, 28.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu26 : 8.1 us, 75.8 sy, 0.0 ni, 16.1 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu27 : 6.7 us, 73.6 sy, 0.0 ni, 19.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu28 : 9.2 us, 74.3 sy, 0.0 ni, 16.4 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu29 : 8.2 us, 73.3 sy, 0.0 ni, 18.5 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu30 : 4.4 us, 73.1 sy, 0.0 ni, 22.4 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu31 : 7.5 us, 69.6 sy, 0.0 ni, 22.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 13217662+total, 3721572 used, 12845504+free, 283228 buffers KiB Swap: 4194300 total, 0 used, 4194300 free. 2242976 cached Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 30349 root 20 0 25.381g 499892 20640 R 2495 0.4 119:11.98 qemu-system-x86 Anything I do? I use perf top, profile to debug the problem. It show me that something like thread deadlock problem. Any I test QEMU with kernel RBD, it work fine. Here are the perf top output on host. --------------------------------------------------------------- PerfTop: 12393 irqs/sec kernel:87.3% exact: 0.0% [4000Hz cycles], (all, 32 CPUs) ------------------------------------------------------------------------------- 75.25% [kernel] [k] _raw_spin_lock 1.17% [kernel] [k] futex_wait_setup 0.86% libc-2.19.so [.] malloc 0.58% [kernel] [k] futex_wake 0.55% libc-2.19.so [.] 0x00000000000ea96f 0.41% [kernel] [k] native_write_msr_safe --------------------------------------------------------------- To manage notifications about this bug go to: https://bugs.launchpad.net/ceph/+bug/1581334/+subscriptions
