On Mon, Aug 17, 2015 at 10:40:35PM +0100, Drew Richardson wrote: > On Wed, Aug 26, 2015 at 05:51:49PM +0100, Will Deacon wrote: > > On Mon, Aug 17, 2015 at 09:58:09PM +0100, Drew Richardson wrote: > > > On Tue, Aug 04, 2015 at 01:15:23AM +0100, Drew Richardson wrote: > > > > Add additional information about hardware events to make counters self > > > > describing. This makes the hardware PMUs easier to use as perf list > > > > contains the possible events instead of users having to refer to > > > > documentation like the ARM TRMs. This could also allow tools like > > > > oprofile to support PMUs without requiring an update. > > > > > > > > Signed-off-by: Drew Richardson <[email protected]> > > > > --- > > > > arch/arm/kernel/perf_event.c | 1 + > > > > arch/arm/kernel/perf_event_v7.c | 617 > > > > ++++++++++++++++++++++++++++++++++++++++ > > > > 2 files changed, 618 insertions(+) > > > > > > Any concerns with merging this? > > > > We should revisit this after the merge window (since the ARM perf code is > > moving out to drivers/) > > Not a problem > > > but I do have reservations about putting all these > > strings into the kernel. Why can't we put this into something like libpfm > > instead? > > > > Will > > > > My intent is to make it easier for people to use hardware counters on > ARM, particularly with new CPUs. Currently, the developer of the tool > needs to extract the event information from the ARM TRMs, add it to > their tool and make a new release. This work is done by multiple > tools, for example for the Cortex-A15: > > http://sourceforge.net/p/perfmon2/libpfm4/ci/master/tree/lib/events/arm_cortex_a15_events.h > http://sourceforge.net/p/oprofile/oprofile/ci/master/tree/events/arm/armv7-ca15/events > https://github.com/ARM-software/gator/blob/master/daemon/events-Cortex-A15.xml > > There are likely more tools, these are the ones I could easily > find. Note that the new ARM Cortex-A72 isn't supported by most of > them. And the perf command line tool doesn't have any of this. > > Once the tool supports the new CPUs events the user needs to make sure > they're running a recent version of the tool that contains these > events for their new ARM CPU. Technically the user could add the event > information themselves and upstream the change, but not all users will > do this. > > So my suggestion to solve the problem is that the kernel can have the > list of events as proposed in the patch. This is already done for some > PMUs like arm-ccn and arm-cci. If the tool doesn't support the > particular CPU, they can fall back to the event list provided by the > kernel. There will be some information missing like user-friendly > descriptions of the events, but it's hopefully enough that users can > do what they need to do and update their tool at a later time. > > I'd be glad to wrap this all in a config option so users can disable > it to reduce bloat. Perhaps there is some other central location > outside the kernel that could store this information? > > Thanks, > > Drew
Will, Have you had a chance to review this again? I also noticed that my x86 machines have something similar, although not as few events as I'm proposing to add. $ ls /sys/bus/event_source/devices/cpu/events/ cycles-ct el-capacity el-start tx-abort tx-conflict cycles-t el-commit mem-loads tx-capacity tx-start el-abort el-conflict mem-stores tx-commit Thanks, Drew -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
