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dcpi2bb(1)

NAME

dcpi2bb - Insert DCPI profile feedback data in an image file

SYNOPSIS

dcpi2bb [-make_bbdb] [-counts] [-pm all] [-load_lat] [<flags>] image-file

DESCRIPTION

Dcpi2bb inserts profile feedback information into an optional part of the executable image for subsequent use by compilers or post-link optimizers like spike(1). If the image was originally compiled with the -feedback option, the compiler will have included an empty basic block data base in the executable. If the image was not compiled for feedback, dcpi2bb can create a basic block data base before inserting profile data.

One must gather profile samples using dcpid(1) before using dcpi2bb. For best results, application training runs should be representative of anticipated production runs. Note: Because DCPI has little overhead, it is often practical to use actual production runs to generate profile feedback information.

FLAGS

-counts
Populate the profile feedback data base with estimated execution frequency counts for each basic block. Note: Because DCPI is a sampling tool, there will be some statistical variation from run to run.

-help
Display a usage message.

-load_lat
Include load latency value samples (if available). These must have been previously gathered by running dcpid(1) in load latency value profiling mode. See dcpildlatency(1).

-make_bbdb
Create a basic block data base from the code structure and relocations in the image.

-scale
By default, an estimated count of 1 denotes P executions, where P is the average sampling period used to gather the samples. With -scale, the estimated basic-block counts are scaled by P.

-trace flag
Enable debug tracing for the specified flag (e.g. alloc, change, check, combine, esli, hash, io, leak, match, merge, name, offset, profile, rank, reorder, weight).

-version
Print dcpi2bb version string.

PROFILE SELECTION FLAGS

By default, this command automatically finds all of the relevant profile files. The following options can be used to guide the search for the profile files.

-db <directory name>
Search for profile files in the specified profile database directory. The directory name should be the same name as the one specified when dcpid was started. If this option is not specified, the directory name is obtained from the DCPIDB environment variable. If neither this option, nor the DCPIDB environment variable are set, the name of the directory used by the last invocation of dcpid on this machine is used. If none of these methods succeed in finding the appropriate directory, and no explicit set of profile files is provided via the -profiles option, then the command fails.

-epoch latest
Search for profile files in the latest epoch. This is the default.

-epoch latest-k
Search for profile files in the "k+1"th oldest epoch. For example, search in the third oldest epoch if -epoch latest-2 is specified.

-epoch <name>
Search for profile files in the named epoch. The epoch name should be the name of a subdirectory corresponding to a single epoch within the profile database directory. Epoch subdirectory names usually take the form YYYYMMDDHHMM (year-month-day-hours-minutes). For example, an epoch started on June 11, 2002 at 22:33 would be named 200206112233. If an epoch is given a symbolic name by creating a symbol link to the actual epoch directory, then the symbolic name can also be used as an argument to the -epoch option.

-epoch all
Search for profile files in all epochs.

-ihost <hostnames...> --

Include just those profile files associated with the specified host names. The list of host names must be terminated either via -- or by the end of the option list. The command prints an error message and fails if both the -ihost and -ehost options are specified.

-ehost <hostnames...> --

Exclude any profile files associated with the specified host names. The list of host names must be terminated either via -- or by the end of the option list. The command prints an error message and fails if both the -ihost and -ehost options are specified.

-label <label>
Search for profile files with the specified label(s) (see dcpilabel(1)). This option can be repeated multiple times. If no labels are specified on the command line, profile file labels are ignored entirely. If any labels are specified on the command line, only profile files that have one of the specified labels are used.

-profiles <file names...> --
Use just the profile files named by the specified file names. The list of profile file names can be terminated either via --, or by the end of the option list. The command prints an error message and fails if the -profiles option is used in conjunction with any of the earlier automatic profile finding options. (Use the automatic profile lookup mechanism, or explicitly name the profile file with the -profile option; but don't do both.)

STATISTIC SELECTION FLAGS

Different kinds of performance counter statistics are available on various models of Alpha CPUs. Alpha 21064/EV4, 21164/EV5 and 21264/EV6 CPUs have traditional aggregate event counters. Alpha 21264A/EV67 and later processors have a mix of some traditional aggregate event counters and newer ProfileMe counters which allow accurate and precise instruction execution profiles on out-of-order processors. (See dcpiprofileme(1) for more information on ProfileMe statistics.)

The default statistic selection on an aggregate counter machine is to select all the aggregate events. The default on a ProfileMe machine is to select ProfileMe retire delay, retire count, !retired (i.e. aborted) count, !notrap (i.e. trap) count, and aggregate cycles.

The options below can be used to select various statistics when available. Use -event for aggregate statistics and -pm for ProfileMe statistics. Note: there can be multiple, mixed -event and -pm specifications. You can also specify the ratio of two statistics (written as stat1::stat2).

-pm pm_stat(+pm_stat)
Select the specified ProfileMe statistic plus any added in by optional +pm_stat specifications. For example, select various trap statistics by specifying the option -pm trap+replays+ldstorder+mispredict.

-pm default(+pm_stat)
Select the default set of ProfileMe statistics plus those added in by +pm_stat specifications. At least one additional statistic is mandatory; -pm default without modifications is extraneous and not allowed. The additional ProfileMe statistics will take the place of the aggregate cycles statistic which is selected by default.

-pm all(-pm_stat)
Select all ProfileMe statistics less those subtracted out. You can repeat the optional -pm_stat specification to deselect multiple ProfileMe statistics. Note: there are a lot of ProfileMe statistics. Unless you deselect a bunch of them, this will select more statistics than are appropriate for human consumption.

-event ag_stat(+ag_stat)
Select the specified aggregate statistic plus any added in by optional +ag_stat specifications. For example, select cycles, icache misses, and data cache misses when the option -event cycles+imiss+dmiss is specified.

-event all(-ag_stat)
Select all aggregate statistics less those subtracted out. You can repeat the optional -ag_stat specification to deselect multiple aggregate statistics.

-allevents
Select profile events corresponding to all event types, both aggregate and ProfileMe. However, if there are ProfileMe events, this will produce a large number of statistics, which in most cases will not be useful.

BUGS

Profiles gathered on an EV6 machine are not currently useful for profile feedback. Because EV6 is an out-of-order machine without ProfileMe performance counters, it is impractical to estimate basic block execution frequencies. Use a 21264A/EV67 (or later) system to generate profile feedback data.

EXAMPLE

dcpid db; run image; dcpiflush
Profile image so DCPI can collect profile feedback data.

dcpi2bb -db db -make_bbdb -counts -pm all image
Run dcpi2bb to insert profile feedback data into executable image.

spike image -feedback image -o image.faster
Run spike(1) to analyze image based on the profile feedback data stored in image and to create a new, optimized image.faster.

SEE ALSO

dcpi(1), dcpi2pix(1), dcpi2ps(1), dcpicalc(1), dcpicat(1), dcpicc(1), dcpicoverage(1), dcpictl(1), dcpid(1), dcpidiff(1), dcpidis(1), dcpiepoch(1), dcpiflow(1), dcpiflush(1), dcpikdiff(1), dcpilabel(1), dcpildlatency(1), dcpilist(1), dcpiprof(1), dcpiprofileme(1), dcpiquit(1), dcpiscan(1), dcpisource(1), dcpistats(1), dcpisumxct(1), dcpitar(1), dcpitopcounts(1), dcpitopstalls(1), dcpiuninstall(1), dcpiupcalls(1), dcpivarg(1), dcpivcat(1), dcpiversion(1), dcpivlst(1), dcpivprofiler(1), dcpiwhatcg(1), dcpix(1), dcpiformat(4), dcpiexclusions(4)

For more information, see the DCPI project home page http://h30097.www3.hp.com/dcpi.

COPYRIGHT

Copyright 1996-2004, Hewlett-Packard Company. All rights reserved.