Frequently Asked Questions and Troubleshooting Tips
This section provides recommendations to obtain the maximum performance from Accelerator Plus.
Use the Latest Release
The performance of the Accelerator Plus scheduler is frequently updated. Using the most current version is recommended.
Use the vwn Wrapper
The wrapper
vwn
(alias for vw -N
) avoids
communication with vovserver. An example is shown below:
% wx run -wrapper vwn sleep 0
The benefit is of using vwn
is speed.
The disadvantage is that jobs that require the -wl option cannot be run. However, this disadvantage may be not be significant, as -wl adds a relatively high load for what it does: -wl requires an extra notify client to handle the event generated when the job terminates.
Disable Wait Reasons
If analyzing what causes wait time in the workload, the wait reason analysis
can be disabled as shown below:
# In policy.tcl
set config(enableWaitReasons) 0
Wait time analysis can then be re-enable as needed as shown below:
% wx cmd vovsh -x 'vtk_server_config enableWaitReasons 1'
### collect some data for a few minutes, then
% wx cmd vovsh -x 'vtk_server_config enableWaitReasons 0'
Disable File Access
Disabling file access is mostly a high-reliability option. By disabling file access,
the vovserver never looks at any of the files in the user
workspaces, which avoids the risk of disk slowness or disk unavailability. An
example is shown below:
% wx cmd vovsh -x 'vtk_server_config disablefileaccess 2'
Reduce Update Rate of Notify Clients
Notify clients, clients that are tapping the event stream from vovserver (such as wx gui,
voveventmon or wx run -wl), are updated
immediately in the inner loop of the scheduler. If the environment includes hundreds
of such clients, it may be beneficial to slow down the update rate by setting the
parameter notifySkip. The default value is 0: no skip.
Typically, the more events that take place, the more events that can be skipped
without notice. For example, if several events are taking place, setting
notifySkip to 100, fewer updates may not be noticed. If the
number of events is small, a one-second delay may be noticed in some updates of the
GUI. skipped without notice.
Note: Regardless of the setting, the maximum time
between updates is one
second.
# In policy.tcl
set config(notifySkip) 100