On Tue, 2012-10-16 at 11:31 -0700, Sukadev Bhattiprolu wrote: > On a side note, how does the kernel on x86 use the 'config' information in > say /sys/bus/event_source/devices/cpu/format/cccr ? On Power7, the raw > code encodes the information such as the PMC to use for the event. Is that > how the 'config' info in Intel is used ? > > Does the 'config' info change from system to system or is it static for > a given event on a given CPU ?
Have a look at commits (tip/master): 641cc938815dfd09f8fa1ec72deb814f0938ac33 a47473939db20e3961b200eb00acf5fcf084d755 43c032febde48aabcf6d59f47cdcb7b5debbdc63 So basically /sys/bus/event_source/devices/cpu/format/event contains something like: config:0-7 Which says that for the 'cpu' PMU, field 'event' fills perf_event_attr::config bits 0 through 7 (for type=PERF_TYPE_RAW). The perf tool syntax for this is: perf stat -e 'cpu/event=0x3c/' This basically allows you to expose bitfields in the 'raw' event format for ease of writing raw events. I do not know if the Power PMU has such or not. Using this, /sys/bus/event_source/devices/cpu/events/cpu-cycles would contain something like: event=0x3c which one can use as: perf stat -e 'cpu/event=cpu-cycles/' perf stat -e 'cpu/cpu-cycles/' The tool will then read the sysfs file, substitute the content to obtain: perf stat -e 'cpu/event=0x3c/' and run with that. Within all this, the perf_event_attr::config* field names are hard-coded special, so 'cpu/config=0xffff/' will always work, even without sysfs format/ specification and is equivalent to the raw event stuff we had before. If the Power PMU lacks any structure to the raw config, you could simply provide sysfs event/ files with: config=0xdeadbeef like content. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
