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Andi Kleen pointed out that the Intel offcore support patches were merged without user-space tool support to the functionality: | | The offcore_msr perf kernel code was merged into 2.6.39-rc*, but the | user space bits were not. This made it impossible to set the extra mask | and actually do the OFFCORE profiling | Andi submitted a preliminary patch for user-space support, as an extension to perf's raw event syntax: | | Some raw events -- like the Intel OFFCORE events -- support additional | parameters. These can be appended after a ':'. | | For example on a multi socket Intel Nehalem: | | perf stat -e r1b7:20ff -a sleep 1 | | Profile the OFFCORE_RESPONSE.ANY_REQUEST with event mask REMOTE_DRAM_0 | that measures any access to DRAM on another socket. | But this kind of usability is absolutely unacceptable - users should not be expected to type in magic, CPU and model specific incantations to get access to useful hardware functionality. The proper solution is to expose useful offcore functionality via generalized events - that way users do not have to care which specific CPU model they are using, they can use the conceptual event and not some model specific quirky hexa number. We already have such generalization in place for CPU cache events, and it's all very extensible. "Offcore" events measure general DRAM access patters along various parameters. They are particularly useful in NUMA systems. We want to support them via generalized DRAM events: either as the fourth level of cache (after the last-level cache), or as a separate generalization category. That way user-space support would be very obvious, memory access profiling could be done via self-explanatory commands like: perf record -e dram ./myapp perf record -e dram-remote ./myapp ... to measure DRAM accesses or more expensive cross-node NUMA DRAM accesses. These generalized events would work on all CPUs and architectures that have comparable PMU features. ( Note, these are just examples: actual implementation could have more sophistication and more parameter - as long as they center around similarly simple usecases. ) Now we do not want to revert *all* of the current offcore bits, as they are still somewhat useful for generic last-level-cache events, implemented in this commit: |
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| Kconfig.cpu | ||
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| Makefile | ||
| Makefile_32.cpu | ||