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[Qemu-devel] vm console often stuck for one or two seconds when the sys


From: yuchangw
Subject: [Qemu-devel] vm console often stuck for one or two seconds when the sys time is high
Date: Tue, 13 Jan 2015 19:49:06 +0800


Hi all.
   Our vm created by qemu is often stuck for one or two seconds.The following is our configuration.

   Qemu:
       QEMU emulator version 2.0.0 (Debian 2.0.0+dfsg-2ubuntu1.1), Copyright (c) 2003-2008 Fabrice Bellar
   Hypervisor System: Ubuntu-14.04-server
   VM System: Centos6.5-x86_64
   VM Config: 8VCPU,24G RAM MEMORY
   We have a busy java process named BusyA in the VM.The BusyA process consume %200 CPU about every 10 seconds.
   And the BusyA process has 200 threads.
   We pin all the busy threads to core 4-7 by the command taskset -p 0xf0  thread_id .in all the busy threads to core 4-7 by the command taskset -p 0xf0  thread_id .
   We write a very simple script to test if stucked.
   script:
           #!/usr/bin/env bash
          i=0
          while read input
          do
               i=`expr $i + 1`
               echo $i
         done

We call this bash_test process and pin it to cpu0 with command "taskset -p 0x01 bash_test_pid"
So we start test by press Enter key.
When the bash_test process is stucked,we get the following monitor info from top.
Tasks: 291 total,  12 running, 279 sleeping,   0 stopped,   0 zombie
Cpu0  :  4.9%us,  9.8%sy,  0.0%ni, 83.2%id,  0.0%wa,  0.0%hi,  2.1%si,
Cpu1  : 10.9%us,  8.8%sy,  0.0%ni, 78.2%id,  0.0%wa,  0.0%hi,  2.1%si,
Cpu2  :  6.9%us, 46.6%sy,  0.0%ni, 35.1%id, 11.3%wa,  0.0%hi,  0.2%si,
Cpu3  :  3.0%us,  0.8%sy,  0.0%ni, 91.5%id,  4.6%wa,  0.0%hi,  0.0%si,
Cpu4  : 17.1%us,  3.2%sy,  0.0%ni, 78.8%id,  0.0%wa,  0.0%hi,  0.9%si,
Cpu5  : 21.4%us,  0.5%sy,  0.0%ni, 77.0%id,  0.0%wa,  0.0%hi,  1.1%si,
Cpu6  : 12.9%us,  1.0%sy,  0.0%ni, 86.1%id,  0.0%wa,  0.0%hi,  0.0%si,
Cpu7  : 17.1%us,  2.3%sy,  0.0%ni, 79.6%id,  0.0%wa,  0.0%hi,  0.9%si,
Mem:  24024140k total,  6104132k used, 17920008k free,   117012k buffer
Swap:  2064376k total,        0k used,  2064376k free,   636348k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND   
 2508 root      20   0 9868m 1.4g  99m S 201.3  6.0  59:26.00 java     

My conclusion is that:
           the bash_test process will be stucked when the %xxsy is high even if the cpu0 is idle.

Is there some way to adjust the qemu or to debug qemu ?
If this is not the right mail list to ask this question,please tell me .

Best Regards!
Yuchang


 



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