PCITOP

The PCITOP package is used to monitor PCI bus utilization.  It pokes
and prods counters in the root bridge chipsets found in a system,
parses the data, and produces a display showing utilization as a
percentage for each root bridge.  Note, that the tool does not show
bandwidth, just the ratio of use to the maximum use possible.

There are two components to the pcitop project, a driver called hplba,
and a user tool called pcitop. The driver provides the pci utilization
counters that the user land tool queries.  The driver exposes the
counters using the sysfs file-system. The user tool reads and writes
these sysfs entries to obtain a count of elapsed time and the time
that the pci bus was in use (reading or writing data).  It then
calculates a ratio of these values to get utilization. The pcitop tool
then displays snapshots of utilization for each PCI bridge in the
system.  The tool uses the acpiphp or pci_slot driver to map PCI slots
to root bridges.

Pcitop operates in two modes.  The first mode is used to present
information about root bridges found in the system.  Here is an
example:

# pcitop -i

0000:4a:00.0   PCI/66 MHz lba id = 0x122e rev=3.2 in use=n ropes=1 cabinet 0
   bay 0 chassis 0 slots 8
0000:49:00.0   PCI-X mode 1/66 MHz lba id = 0x122e rev=3.2 in use=y ropes=1 
   cabinet n/a bay n/a chassis n/a slots n/a
0000:0a:00.0   PCI/66 MHz lba id = 0x122e rev=3.2 in use=n ropes=2 cabinet 0 
   bay 0 chassis 0 slots 7
0000:01:00.0   PCI-X mode 1/66 MHz lba id = 0x122e rev=3.2 in use=y ropes=1
    cabinet 0 bay 0 chassis 0 slots 10,9
0000:00:00.0   PCI/66 MHz lba id = 0x122e rev=3.2 in use=y ropes=1 
   cabinet n/a bay n/a chassis n/a slots n/a
0000:c4:00.0   PCIe/x8 lba id = 0x4037 rev=2.2 in use=y ropes=4 
   cabinet n/a bay n/a chassis n/a slots n/a
0000:4f:00.0   PCIe/x8 lba id = 0x4037 rev=2.2 in use=y ropes=2 
   cabinet n/a bay n/a chassis n/a slots n/a
0000:0f:00.0   PCIe/x8 lba id = 0x4037 rev=2.2 in use=y ropes=4 
   cabinet n/a bay n/a chassis n/a slots n/a

The second mode is used to display bus utilization.  It measures
utilization over a given interval and outputs the utilization for each
root bridge.  Various filters can be applied to limit the number of
root bridges displayed. Example:

# pcitop
-------------------------------------------------------------------------------
bridge    0000:4a:00.0  0000:49:00.0  0000:0a:00.0  0000:01:00.0  0000:00:00.0
type      PCI           PCI-X mode 1  PCI           PCI-X mode 1  PCI         
speed     66 MHz        66 MHz        66 MHz        66 MHz        66 MHz     
slots     8             n/a           7             10, 9         n/a        
ropes     1             1             2             1             1          
------------------------------------------------------------------------------
          000.00%       003.11%       000.00%       000.01%       001.42%     
          000.00%       003.06%       000.00%       000.00%       000.04%     
          000.00%       002.97%       000.00%       000.00%       001.34%     
          000.00%       002.85%       000.00%       000.00%       000.11%     
          000.00%       003.05%       000.00%       000.00%       001.28%     

PCI Utilization counters are very system specific. As such, a
different driver must be used for each architecture.  Currently there
is only one driver available, hplba, for Hewlett-Packard Itanium
(IA-64) systems running Linux with kernel versions of 2.6.16 or later.