 |
HP OpenVMS System Analysis Tools Manual
SPL LOAD
Loads the SPL$DEBUG execlet. This must be done prior to starting
spinlock tracing.
Format
SPL LOAD
Parameters
None.
Qualifiers
None.
Description
The SPL LOAD command loads the SPL$DEBUG execlet, which contains the
tracing routines.
Example
|
SDA> SPL LOAD
SPL$DEBUG load status = 00000001
|
SPL SHOW COLLECT
Displays the collected spinlock data.
Format
SPL SHOW COLLECT [/RATES|/TOTALS]
Parameters
None.
Qualifiers
/RATES
Reports activity as a rate per second and hold/spin time as a
percentage of time. This is the default.
/TOTALS
Reports activity as a count and hold/spin time as cycles.
Description
The SPL SHOW COLLECT command displays the collected spinlock data. It
displays first a summary on a per-CPU basis, followed by the callers of
the specific spinlock. This second list is sorted by the top consumers
of the spinlock (in percent of time held). These displays show average
spinlock hold and spinlock wait time in system cycles.
Example
SPL SHOW TRACE
Displays spinlock tracing information.
Format
SPL SHOW TRACE
[/[NO]SPINLOCK=spinlock|/[NO]FORKLOCK=forklock
|/[NO]ACQUIRE|/RATES |/[NO]RELEASE|/[NO]WAIT
|/[NO]FRKDSPTH|/[NO]FRKEND
|/SUMMARY|/CPU=n
|/TOP=n|/TOTALS]
Parameters
None.
Qualifiers
/SPINLOCK=spinlock
/NOSPINLOCK
The /SPINLOCK=n qualifier specifies the display of a specific
spinlock, for example, /SPINLOCK=LCKMGR or /SPINLOCK=SCHED.
The /NOSPINLOCK qualifier specifies that no spinlock trace information
be displayed. If omitted, all spinlock trace entries are decoded and
displayed.
/FORKLOCK=forklock
/NOFORKLOCK
The /FORKLOCK=forklock qualifier specifies the display of a
specific forklock, for example, /FORKLOCK=IOLOCK8 or /FORKLOCK=IPL8.
The /NOFORKLOCK qualifier specifies that no forklock trace information
be displayed. If omitted, all fork trace entries are decoded and
displayed.
/ACQUIRE
/NOACQUIRE
The /ACQUIRE qualifier displays any spinlock acquisitions.
The /NOACQUIRE qualifier ignores any spinlock acquisitions.
/RATES
Reports activity as a rate per second and hold/spin time as a
percentage of time. This is the default.
/RELEASE
/NORELEASE
The /RELEASE qualifier displays any spinlock releases.
The /NORELEASE qualifier ignores any spinlock releases.
/TOTALS
Reports activity as a count and hold/spin time as cycles.
/WAIT
/NOWAIT
The /WAIT qualifier displays any spinwait operations.
The /NOWAIT qualifier ignores any spinwait operations.
/FRKDSPTH
/NOFRKDSPTH
The /FRKDSPTH qualifier displays all invocations of fork routines
within the fork dispatcher. This is the default.
The /NOFRKDSPTH qualifier ignores all of the operations of the
/FRKDSPTH qualifier.
/FRKEND
/NOFRKEND
The /FRKEND qualifier displays all returns from fork routines within
the fork dispatcher. This is the default.
The /NOFRKEND qualifier ignores all operations of the /FRKEND qualifier.
/CPU=n
Specifies the display of information for a specific CPU only, for
example, /CPU=5 or /CPU=PRIMARY. By default, all trace entries for all
CPUs are displayed.
/SUMMARY
Steps through the entire trace buffer and displays a summary of all
spinlock and forklock activity. It also displays the top ten callers.
/TOP=n
Displays a different number other than the top ten callers or fork PCs.
By default, the top ten are displayed. This qualifier is only useful
when you also specify the /SUMMARY qualifier.
Description
The SPL SHOW TRACE command displays spinlock tracing information. The
latest acquired or released spinlock is displayed first, and then the
trace buffer is stepped backwards in time.
By default, all trace entries will be displayed, but you can use
qualifiers to select only certain entries.
Since this is not a time critical activity and a table lookup has to be
done anyway to translate the SPL address to a spinlock name, commands
like /SPINLOCK=(SCHED,IOLOCK8) do work. /SUMMARY will step the entire
trace buffer and display a summary of all spinlock activity, along with
the top-ten callers' PCs. You can use /TOP=n to display a different
number of the top ranked callers.
Examples
| Callout |
Meaning |
|
1
|
Shows timestamps that are collected as system cycle counters (SCC) and
then displayed with an accuracy down to microseconds. Each CPU is
incrementing its own SCC as soon as it is started, so there is some
difference between different CPUs' system cycle counters. The standard
system time is incremented only every 10 Msec and as such is not exact
enough. Adjusting the SCC to the specific CPU's system time and
translating it into an accurate timestamp will thus sometimes display
times out of order for different CPUs. However, for the same CPU ID,
the timestamps are accurate.
|
|
2
|
Shows the physical CPU ID of the CPU logging the trace entry.
|
|
3
|
Shows the address of the spinlock fork. If it is a static one, its name
is displayed; otherwise, it is marked as ???.
|
|
4
|
Shows the caller's PC address that acquired or released the spinlock,
or the fork PC if the trace entry is a forklock. Symbolization is
attempted, so a READ/EXECUTIVE might help to display a routine name,
instead of simply a module and offset.
|
|
5
|
Shows the EPID, which is the external PID of the process generating the
trace entry. If an interrupt or fork was responsible for the entry,
then a zero EPID is displayed.
|
|
6
|
Shows the trace operation. For a spinlock, which was acquired without
going through a spinwait, there is a matching acquire/release pair of
trace entries for the same CPU ID for a given spinlock. If a spinlock
is held, it cannot be acquired immediately, so there is also a spinwait
trace entry for this pair. The different variations of the acquire and
release operations are distinguished, as are the same spinlocks if they
are acquired recursively multiple times.
|
|
7
|
Shows the address of the trace buffer entry, in case there is a need to
access the raw and undecoded trace data.
|
| Callout |
Meaning |
|
8
|
Shows the summary information by stepping through the whole trace
buffer, and displaying a single line of information for each spinlock.
If the percent of spin wait is very high, then a spinlock is a
candidate for high contention.
|
|
9
|
For each spinlock in the summary display, the top ten callers' PCs are
displayed along with the number of spinlock acquisitions and releases,
as well as spinwait counts and the number of multiple acquisitions of
the same spinlock.
|
| Callout |
Meaning |
|
10
|
The forklock summary displays the number of fork operations on a
specific CPU for each forklock. For each forklock, the top ten fork PC
addresses are displayed, along with the minimum, maximum and average
duration of the fork operation in system cycles. The percent of time
spent in a given fork routine is displayed along with the percent of
time for the forklock.
|
SPL START COLLECT
Starts to collect spinlock information a longer period of time than
will fit into the trace buffer.
Format
SPL START COLLECT [/SPINLOCK=spinlock|/ADDRESS=n]
Parameters
None.
Qualifiers
/SPINLOCK=spinlock
Specifies the tracing of a specific spinlock, for example,
/SPINLOCK=LCKMGR or /SPINLOCK=SCHED.
/ADDRESS=n
Specifies the tracing of a specific spinlock by address.
Description
The SPL START COLLECT command starts a collection of spinlock
information for a longer period of time than will fit into the trace
buffer. You need to enable spinlock tracing before a spinlock
collection can be started. On a system with heavy activity, the trace
buffer typically can only hold a relatively small time window of
spinlock information. In order to collect spinlock information over a
longer time period, a collection can be started. The collection tries
to catch up with the running trace index and save the spinlock
information into a balanced tree within the virtual address space of
the process performing the spinlock collection. Either use the name of
a static spinlock, or supply the address of a dynamic spinlock, for
which information should be gathered.
The trace entries are kept in the trace buffer, which is allocated from
S2 space, hence there is no disruption, if tracing is started from
within SDA and then the user exits from SDA. However, for the longer
period data collection, the information is kept in process-specific
memory, thus a user needs to stay within SDA; otherwise the data
collection is automatically terminated by SDA's image rundown. You can
collect data for two or more spinlocks simultaneously, by using a
separate process for each collection.
Examples
| #1 |
SDA> SPL START COLLECT
Use /SPINLOCK=name or /ADDRESS=n to specify which spinlock info needs to be collected...
|
This example shows that you need to supply either a spinlock name of a
static spinlock, or the address of a dynamic spinlock, if you want to
collect information over a long period of time.
| #2 |
SDA> SPL START COLLECT/SPINLOCK=LCKMGR
|
This example shows the command line to start to collect information on
the usage of the LCKMGR spinlock.
SPL START TRACE
Enables spinlock tracing.
Format
SPL START TRACE [/[NO]SPINLOCK=spinlock|/[NO]FORKLOCK=forklock
|/BUFFER=pages|/[NO]ACQUIRE|
|/[NO]RELEASE|/[NO]WAIT|/[NO]FRKDSPTH
|/[NO]FRKEND|/CPU=n]
Parameters
None.
Qualifiers
/SPINLOCK=spinlock
/NOSPINLOCK
The /SPINLOCK=spinlock qualifier specifies the tracing of a
specific spinlock, for example, /SPINLOCK=LCKMGR or /SPINLOCK=SCHED.
The /NOSPINLOCK qualifier disables spinlock tracing and does not
collect any spinlock data. If omitted, all spinlocks are traced.
/FORKLOCK=forklock
/NOFORKLOCK
The /FORKLOCK=forklock qualifier specifies the tracing of a
specific forklock, for example, /FORKLOCK=IOLOCK8 or /FORKLOCK=IPL8.
The /NOFORKLOCK qualifier disables forklock tracing and does not
collect any forklock data. If omitted, all forks are traced.
/BUFFER=pages
Specifies the size of the trace buffer (in page units). It defaults to
128 pages, which is equivalent to 1MB, if omitted.
/ACQUIRE
/NOACQUIRE
The /ACQUIRE qualifier traces any spinlock acquisitions. This is the
default.
The /NOACQUIRE qualifier ignores any spinlock acquisitions.
/RELEASE
/NORELEASE
The /RELEASE qualifier traces any spinlock releases. This is the
default.
The /NORELEASE qualifier ignores any spinlock releases.
/WAIT
/NOWAIT
The /WAIT qualifier traces any spinwait operations. This is the default.
The /NOWAIT qualifier ignores any spinwait operations.
/FRKDSPTH
/NOFRKDSPTH
The /FRKDSPTH qualifier traces all invocations of fork routines within
the fork dispatcher. This is the default.
The /NOFRKDSPTH qualifier ignores all of the /FRKDSPTH operations.
/FRKEND
/NOFRKEND
The /FRKEND qualifier traces all returns from fork routines within the
fork dispatcher. This is the default.
The /NOFRKEND qualifier ignores all of the operations of the /FRKEND
qualifier.
/CPU=n
Specifies the tracing of a specific CPU only, for example, /CPU=5 or
/CPU=PRIMARY. By default, all CPUs are traced.
Description
The SPL START TRACE command enables spinlock and fork tracing. By
default all spinlocks and forks are traced and a 128 page (1MByte)
trace buffer is allocated and used as a ring buffer.
Examples
| #1 |
SDA> SPL START TRACE/BUFFER=1000
Tracing started... (Spinlock = 00000000, Forklock = 00000000)
|
This example shows how to enable a tracing for all spinlock and
forklock operations into a 8 MByte trace buffer.
| #2 |
SDA> SPL START TRACE/CPU=PRIMARY/SPINLOCK=SCHED /NOFORKLOCK
Tracing started... (Spinlock = 810AF600, Forklock = 00000000)
|
This example shows how to trace only SCHED spinlock operations on the
primary CPU.
| #3 |
SDA> SPL START TRACE /NOSPINLOCK /FORKLOCK=IPL8
Tracing started... (Spinlock = 00000000, Forklock = 863A4C00)
|
This example shows how to trace only fork operations to IPL8.
SPL STOP COLLECT
Stops the spinlock collection, but does not stop spinlock tracing.
Format
SPL STOP COLLECT
Parameters
None.
Qualifiers
None.
Description
The SPL STOP COLLECT command stops the data collection, but does not
affect tracing. This allows the user to start another collection for a
different spinlock during the same trace run.
Example
SPL STOP TRACE
Disables spinlock tracing, but it does not deallocate the trace buffer.
Format
SPL STOP TRACE
Parameters
None.
Qualifiers
None.
Description
The SPL STOP TRACE command stops tracing, but leaves the trace buffer
allocated for further analysis.
Example
|
SDA> SPL STOP TRACE
Tracing stopped...
|
SPL UNLOAD
Unloads the SPL$DEBUG execlet and performs cleanup. Tracing is
automatically disabled and the trace buffer deallocated.
Format
SPL UNLOAD
Parameters
None.
Qualifiers
None.
Description
The SPL UNLOAD command disables the tracing or collection functionality
with a delay to a state of quiescence. This ensures that all pending
trace operations in progress have finished before the trace buffer is
deallocated. Finally the SPL UNLOAD command unloads the SPL$DEBUG
execlet.
Example
|
SDA> SPL UNLOAD
SPL$DEBUG unload status = 00000001
|
|
