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dcpi2pix(1)

NAME

dcpi2pix - Translate DCPI profile data to pixie format

SYNOPSIS

dcpi2pix [<flags>] [-scale] [-version] image-file

DESCRIPTION

Dcpi2pix processes an image file and one or more DCPI profiles for that image and produces a pixie-style output file (*.Counts) containing the relative execution counts for each basic block in the image.

The execution counts are estimated from cycles samples using heuristics as in dcpicalc(1). When a basic block's estimated execution count has too low a confidence, dcpi2pix arbitrarily writes a count of 0 for the block in the Counts file. Users will typically want to use the -conf_low option to include low-confidence data.

Before running dcpi2pix, one must gather cycles samples using dcpid(1) and construct a Addrs file using pixie.

Since DCPI is a sampling-based profiling system and pixie produces exact basic block execution counts through instrumentation, profiles produced by dcpi2pix might confuse downstream tools. In particular, if a downstream tool depends on having exact counter values, with basic block counts that satisfy the flow constraints of the control flow graph, then it might become confused when confronted by a dcpi2pix-generated Counts, which will not have this property (see BUGS, below, for an example). If the tools use the basic block counts only to determine which parts of the program were frequently executed, however, the output produced by dcpi2pix should work fine.

Pixie files contain an embedded CPU type in the profile data. Dcpi2pix determines the cpu type using the cpu type of the machine on which the first specified sample file was gathered.

FLAGS

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

-version
Print dcpi2pix 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.

EXECUTION COUNT AND STALL ANALYSIS FLAGS

The following options can be used to control the heuristics for estimating execution counts and identifying the causes of stalls.

-conf_low
Generate low, medium, and high confidence data.

-conf_med
Generate medium and high confidence data. (default)

-conf_high
Generate only high confidence data.

-cross_procedure [optimistic | pessimistic | selective]
Choose what assumption to make when a procedure call boundary is encountered while looking for reasons to explain dynamic stalls. A procedure call boundary is either a call made by the procedure being analyzed or the beginning or end of that procedure. With pessimistic, assume that whatever happens outside the analyzed procedure can cause a dynamic stall inside it. With optimistic, assume that it cannot. With selective, the assumption is based on standard procedure call convention. (The default is optimistic.)

-do_gp
Use a (non-linear time) constraint solver to exploit global flow constraints when estimating execution counts. The estimates may still violate flow constraints.

-tab foo.tab
Get execution counts from output of dcpix(1) instead of making estimates, which may be inaccurate. Requires a .xct file.

-xct foo.xct
Get execution counts from output of dcpix(1) instead of making estimates, which may be inaccurate. Requires a .tab file.

-xct_factor num
Scales counts from .xct files by num. Useful when you run a program once under dcpix(1) but multiple (num) times under dcpid(1) to get more samples. Used in conjunction with -tab and -xct.

BUGS

Using pixstats(1) with profiles generated by dcpi2pix is known to give incorrect procedure-level information. Pixstats relies on having exact basic-block counts and only checks to see if a basic block starts a new procedure when the basic block's count is bigger than 0. If the entry basic block for a procedure does not accrue any samples during profiling using DCPI, then the basic block's effects will be incorrectly attributed to a previous procedure in the image.

EXAMPLE

pixie image
Run pixie(1) over executable image, producing the file image.Addrs containing the address of each basic block in image, and the pixified executable file image.pixie. The image.pixie file can be deleted since it is not needed by dcpi2pix.

dcpid db; run image; dcpiflush
Get cycles samples for image.

dcpi2pix -conf_low image -db db
Run dcpi2pix over executable image and cycles samples in db, producing the pixie-format file image.Counts. Note that dcpi2pix automatically loads the image.Addrs file generated by pixie.

pixstats image
Run pixstats(1) over executable image and image.Counts, generating a program execution analysis report.

SEE ALSO

dcpi(1), dcpi2bb(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.