Messages in this thread | | | Subject | Re: [PATCH 1/4] perf: Add memory load/store events generic code | From | Peter Zijlstra <> | Date | Wed, 06 Jul 2011 15:58:38 +0200 |
| |
On Wed, 2011-07-06 at 09:02 +1000, Paul Mackerras wrote: > On Tue, Jul 05, 2011 at 02:03:38PM +0200, Peter Zijlstra wrote: > > On Mon, 2011-07-04 at 10:44 +0200, Peter Zijlstra wrote: > > > Anton, Paulus, IIRC PowerPC had some sort of Data-Source indication, > > > would you have some docs available on the PowerPC PMU? > > > > Going through > > http://www.power.org/resources/downloads/PowerISA_V2.06B_V2_PUBLIC.pdf > > > > Book III-S, Appendix B > > > > I can only find the SDAR thing (which I assume is what PERF_SAMPLE_DATA > > uses) but no mention of extra bits describing where the data was sourced > > from. For some reason I had the impression PPC64 had the capability to > > tell if a load/store was from/to L1/2/3/DRAM etc. > > > > Now since the above document is in fact not an exhaustive spec of a > > particular chip but more an outline of what a regular ppc64 chip should > > have, with lots of room for implementation specific extensions it > > doesn't say much at all. > > > > So do you know of such a feature for PPC64 and if so, where's the > > docs? :-) > > Unfortunately the P7 PMU documentation is not available publicly yet. :(
Are the P6/P6+ PMU docs? That at least would give me something to look at.
> There are events that can be used to count how many times data or > instructions get loaded from different places in the memory > subsystem. There are 15 separate DATA_FROM_xxx events, for instance, > that count things like "number of times data was loaded from L2 or L3 > cache on another chip and the cache line was in shared state". > They're great if you want fine detail on memory traffic but perhaps > not so good if you want a broad overview (there are separate events > for L1 and L2 accesses and misses though). > > I've attached a table of P7 PMU events. Look for the PM_DATA_FROM_xxx > and PM_INST_FROM_xxx events.
Ok, so those are regular events and perf covers that capability.
The thing we're talking about is Intel PEBS Load Latency/Precise Store and AMD IBS where together with a mem op retired event (mem loads retired for Load-Latency, mem stores retired for Precise Store) provides an additional field describing where the load/store was sourced from.
Such additional data would require the addition of a PERF_SAMPLE_SOURCE field or similar, for some reason or other I was under the impression some of the PPC chips had something similar. But if not, it saves us having to worry about that.
| |