[Qemu-devel] [Bug 692570] Re: APIC Latency causing BSOD.

[Thomas Huth]

Since there hasn't been an answer to this within the last years, it
looks like nobody here knows about Proxmox problems. So let's close this
ticket...

** Changed in: qemu
       Status: New => Invalid

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https://bugs.launchpad.net/bugs/692570

Title:
  APIC Latency causing BSOD.

Status in QEMU:
  Invalid

Bug description:
  I have a Proxmox Server with the following specs:

  Version:

  pve-manager: 1.7-10 (pve-manager/1.7/5323)
  running kernel: 2.6.32-4-pve
  proxmox-ve-2.6.32: 1.7-28
  pve-kernel-2.6.32-4-pve: 2.6.32-28
  qemu-server: 1.1-25
  pve-firmware: 1.0-9
  libpve-storage-perl: 1.0-16
  vncterm: 0.9-2
  vzctl: 3.0.24-1pve4
  vzdump: 1.2-9
  vzprocps: 2.0.11-1dso2
  vzquota: 3.0.11-1
  pve-qemu-kvm: 0.13.0-2
  ksm-control-daemon: 1.0-4

  VM Configuration:

  name: TS64
  ide2: none,media=cdrom
  bootdisk: ide0
  ostype: w2k3
  ide0: data:vm-104-disk-1
  memory: 10240
  sockets: 1
  vlan0: virtio=C6:4C:B3:BB:AD:67
  onboot: 1
  cores: 4
  boot: cad
  freeze: 0
  cpuunits: 1000
  acpi: 1
  kvm: 1

  CPU 2x Xeon Quad Core E5620 2.4GHZ Processors:

  processor : 0
  vendor_id : GenuineIntel
  cpu family : 6
  model : 44
  model name : Intel(R) Xeon(R) CPU E5620 @ 2.40GHz
  stepping : 2
  cpu MHz : 2400.323
  cache size : 12288 KB
  physical id : 0
  siblings : 8
  core id : 9
  cpu cores : 4
  apicid : 19
  initial apicid : 19
  fpu : yes
  fpu_exception : yes
  cpuid level : 11
  wp : yes
  flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat 
pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall pdpe1gb rdtscp lm 
constant_tsc arch_perfmon pebs bts rep_good xtopology nonstop_tsc aperfmperf 
pni dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 
sse4_2 popcnt lahf_lm ida arat tpr_shadow vnmi flexpriority ept vpid
  bogomips : 4800.19
  clflush size : 64
  cache_alignment : 64
  address sizes : 40 bits physical, 48 bits virtual
  power management:

  Performance:

  CPU BOGOMIPS: 76803.21
  REGEX/SECOND: 850066
  HD SIZE: 33.96 GB (/dev/mapper/pve-root)
  BUFFERED READS: 333.03 MB/sec
  AVERAGE SEEK TIME: 6.10 ms
  FSYNCS/SECOND: 2948.85
  DNS EXT: 131.42 ms
  DNS INT: 1.28 ms

  I've been successfully running 2 Windows 2003 32-Bit Standard Edition
  Servers on this server for over a month now. Both were migrations from
  actual physical servers. However, I've continued to receive random
  crashes on a Windows 2003 64-bit standard edition running terminal
  services, which was a fresh install. The server runs fine for hours
  under a decent load (20 users) and then will crash with a 3B bug check
  code (System_Service_Exception). I opened a ticket with Microsoft and
  submitted multiple memory dumps and their engineers suggested the
  following:

  Dump Analyses Result:
  ===================

  What happened is that the OS initiated an APIC /software interrupt.
  This is handled by the APIC in real hardware. In your Virtual
  Environment case where you are using Linux based VM – Proxmox, the VM
  implementation somehow has to make it happen on a virtual machine with
  the same latency in the virtual APIC. The problem is that there is a
  latency between when it was initiated and when it happened.

  
  Below are the details for understanding the process or concept of APIC 
interrupts:

  What the Local APIC Is
  The Local APIC (LAPIC) is a circuit that is part of the CPU chip. It contains 
these basic elements:
  A mechanism for generating
  1. interrupts
  2. A mechanism for accepting interrupts
  3. A timer

  If you have a multiprocessor system, the APIC's are wired together so
  they can communicate. So the LAPIC on CPU 0 can communicate with the
  LAPIC on CPU 1, etc.

  
  What the IO APIC Is

  This is a separate chip that is wired to the Local APIC's so it can forward 
interrupts on to the CPU chips. It is programmed similar to the 8259's but has 
more flexibility.
  It is wired to the same bus as the Local APIC's so it can communicate with 
them.

  Note:- In our scenario, it’s all Virtualized interrupts or calls because of 
hypervisor in picture and thus we need to contact the VM application vendor to 
get a check of this latency issue in APIC interrupt.
  ------------------------------------------------End of 
Message----------------------------------


  Their engineers are saying that there is a latency issue with APIC.
  I'm not exactly sure how this can be corrected. Is this a known issue
  and is their a solution to this problem. I love Proxmox, but my main
  reason for using it was to upgrade my terminal server to better
  hardware, while leveraging it for other virtual machines as well.  The
  forum administrator for Proxmox, suggested I bring this issue to your
  attention.

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