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Diffstat (limited to 'tools/perf/Documentation/perf-mem.txt')
| -rw-r--r-- | tools/perf/Documentation/perf-mem.txt | 176 |
1 files changed, 143 insertions, 33 deletions
diff --git a/tools/perf/Documentation/perf-mem.txt b/tools/perf/Documentation/perf-mem.txt index 19862572e3f2..4d164836d094 100644 --- a/tools/perf/Documentation/perf-mem.txt +++ b/tools/perf/Documentation/perf-mem.txt @@ -21,22 +21,17 @@ and stores are sampled. Use the -t option to limit to loads or stores. Note that on Intel systems the memory latency reported is the use-latency, not the pure load (or store latency). Use latency includes any pipeline -queueing delays in addition to the memory subsystem latency. +queuing delays in addition to the memory subsystem latency. On Arm64 this uses SPE to sample load and store operations, therefore hardware and kernel support is required. See linkperf:perf-arm-spe[1] for a setup guide. Due to the statistical nature of SPE sampling, not every memory operation will be sampled. -OPTIONS -------- -<command>...:: - Any command you can specify in a shell. - --i:: ---input=<file>:: - Input file name. +On AMD this use IBS Op PMU to sample load-store operations. +COMMON OPTIONS +-------------- -f:: --force:: Don't do ownership validation @@ -45,24 +40,9 @@ OPTIONS --type=<type>:: Select the memory operation type: load or store (default: load,store) --D:: ---dump-raw-samples:: - Dump the raw decoded samples on the screen in a format that is easy to parse with - one sample per line. - --x:: ---field-separator=<separator>:: - Specify the field separator used when dump raw samples (-D option). By default, - The separator is the space character. - --C:: ---cpu=<cpu>:: - Monitor only on the list of CPUs provided. Multiple CPUs can be provided as a - comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2. Default - is to monitor all CPUS. --U:: ---hide-unresolved:: - Only display entries resolved to a symbol. +-v:: +--verbose:: + Be more verbose (show counter open errors, etc) -p:: --phys-data:: @@ -73,6 +53,9 @@ OPTIONS RECORD OPTIONS -------------- +<command>...:: + Any command you can specify in a shell. + -e:: --event <event>:: Event selector. Use 'perf mem record -e list' to list available events. @@ -85,17 +68,144 @@ RECORD OPTIONS --all-user:: Configure all used events to run in user space. --v:: ---verbose:: - Be more verbose (show counter open errors, etc) - --ldlat <n>:: - Specify desired latency for loads event. Supported on Intel and Arm64 - processors only. Ignored on other archs. + Specify desired latency for loads event. Supported on Intel, Arm64 and + some AMD processors. Ignored on other archs. + + On supported AMD processors: + - /sys/bus/event_source/devices/ibs_op/caps/ldlat file contains '1'. + - Supported latency values are 128 to 2048 (both inclusive). + - Latency value which is a multiple of 128 incurs a little less profiling + overhead compared to other values. + - Load latency filtering is disabled by default. + +REPORT OPTIONS +-------------- +-i:: +--input=<file>:: + Input file name. + +-C:: +--cpu=<cpu>:: + Monitor only on the list of CPUs provided. Multiple CPUs can be provided as a + comma-separated list with no space: 0,1. Ranges of CPUs are specified with - + like 0-2. Default is to monitor all CPUS. + +-D:: +--dump-raw-samples:: + Dump the raw decoded samples on the screen in a format that is easy to parse with + one sample per line. + +-s:: +--sort=<key>:: + Group result by given key(s) - multiple keys can be specified + in CSV format. The keys are specific to memory samples are: + symbol_daddr, symbol_iaddr, dso_daddr, locked, tlb, mem, snoop, + dcacheline, phys_daddr, data_page_size, blocked. + + - symbol_daddr: name of data symbol being executed on at the time of sample + - symbol_iaddr: name of code symbol being executed on at the time of sample + - dso_daddr: name of library or module containing the data being executed + on at the time of the sample + - locked: whether the bus was locked at the time of the sample + - tlb: type of tlb access for the data at the time of the sample + - mem: type of memory access for the data at the time of the sample + - snoop: type of snoop (if any) for the data at the time of the sample + - dcacheline: the cacheline the data address is on at the time of the sample + - phys_daddr: physical address of data being executed on at the time of sample + - data_page_size: the data page size of data being executed on at the time of sample + - blocked: reason of blocked load access for the data at the time of the sample + + And the default sort keys are changed to local_weight, mem, sym, dso, + symbol_daddr, dso_daddr, snoop, tlb, locked, blocked, local_ins_lat. + +-F:: +--fields=:: + Specify output field - multiple keys can be specified in CSV format. + Please see linkperf:perf-report[1] for details. + + In addition to the default fields, 'perf mem report' will provide the + following fields to break down sample periods. + + - op: operation in the sample instruction (load, store, prefetch, ...) + - cache: location in CPU cache (L1, L2, ...) where the sample hit + - mem: location in memory or other places the sample hit + - dtlb: location in Data TLB (L1, L2) where the sample hit + - snoop: snoop result for the sampled data access + + Please take a look at the OUTPUT FIELD SELECTION section for caveats. + +-T:: +--type-profile:: + Show data-type profile result instead of code symbols. This requires + the debug information and it will change the default sort keys to: + mem, snoop, tlb, type. + +-U:: +--hide-unresolved:: + Only display entries resolved to a symbol. + +-x:: +--field-separator=<separator>:: + Specify the field separator used when dump raw samples (-D option). By default, + The separator is the space character. In addition, for report all perf report options are valid, and for record all perf record options. +OVERHEAD CALCULATION +-------------------- +Unlike linkperf:perf-report[1], which calculates overhead from the actual +sample period, perf-mem overhead is calculated using sample weight. E.g. +there are two samples in perf.data file, both with the same sample period, +but one sample with weight 180 and the other with weight 20: + + $ perf script -F period,data_src,weight,ip,sym + 100000 629080842 |OP LOAD|LVL L3 hit|... 20 7e69b93ca524 strcmp + 100000 1a29081042 |OP LOAD|LVL RAM hit|... 180 ffffffff82429168 memcpy + + $ perf report -F overhead,symbol + 50% [.] strcmp + 50% [k] memcpy + + $ perf mem report -F overhead,symbol + 90% [k] memcpy + 10% [.] strcmp + +OUTPUT FIELD SELECTION +---------------------- +"perf mem report" adds a number of new output fields specific to data source +information in the sample. Some of them have the same name with the existing +sort keys ("mem" and "snoop"). So unlike other fields and sort keys, they'll +behave differently when it's used by -F/--fields or -s/--sort. + +Using those two as output fields will aggregate samples altogether and show +breakdown. + + $ perf mem report -F mem,snoop + ... + # ------ Memory ------- --- Snoop ---- + # RAM Uncach Other HitM Other + # ..................... .............. + # + 3.5% 0.0% 96.5% 25.1% 74.9% + +But using the same name for sort keys will aggregate samples for each type +separately. + + $ perf mem report -s mem,snoop + # Overhead Samples Memory access Snoop + # ........ ............ ....................................... ............ + # + 47.99% 1509 L2 hit N/A + 25.08% 338 core, same node Any cache hit HitM + 10.24% 54374 N/A N/A + 6.77% 35938 L1 hit N/A + 6.39% 101 core, same node Any cache hit N/A + 3.50% 69 RAM hit N/A + 0.03% 158 LFB/MAB hit N/A + 0.00% 2 Uncached hit N/A + SEE ALSO -------- linkperf:perf-record[1], linkperf:perf-report[1], linkperf:perf-arm-spe[1] |