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CPPC defined in section 8.4.7 of ACPI 6.0 specification suggests "To amortize the cost of PCC transactions, OSPM should read or write all PCC registers via a single read or write command when possible" This patch enables opportunistic batching of frequency transition requests whenever the request happen to overlap in time. Currently the access to pcc is serialized by a spin lock which does not scale well as we increase the number of cores in the system. This patch improves the scalability by allowing the differnt CPU cores to update PCC subspace in parallel and by batching requests which will reduce the certain types of operation(checking command completion bit, ringing doorbell) by a significant margin. Profiling shows significant improvement in the overall effeciency to service freq. transition requests. With this patch we observe close to 30% of the frequency transition requests being batched with other requests while running apache bench on a ARM platform with 6 independent domains(or sets of related cpus). Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> |
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| .. | ||
| platform | ||
| acbuffer.h | ||
| acconfig.h | ||
| acexcep.h | ||
| acnames.h | ||
| acoutput.h | ||
| acpi_bus.h | ||
| acpi_drivers.h | ||
| acpi_io.h | ||
| acpi_lpat.h | ||
| acpi_numa.h | ||
| acpi.h | ||
| acpiosxf.h | ||
| acpixf.h | ||
| acrestyp.h | ||
| actbl1.h | ||
| actbl2.h | ||
| actbl3.h | ||
| actbl.h | ||
| actypes.h | ||
| acuuid.h | ||
| apei.h | ||
| button.h | ||
| cppc_acpi.h | ||
| ghes.h | ||
| hed.h | ||
| pcc.h | ||
| pdc_intel.h | ||
| processor.h | ||
| reboot.h | ||
| video.h | ||