09 Sep, 2016
1 commit
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Since struct cpudata is defined in a header file, add prefix cppc_ to
make it not a generic name. Otherwise it causes compile issue in locally
define structure with the same name.Signed-off-by: Srinivas Pandruvada
Signed-off-by: Rafael J. Wysocki
31 Aug, 2016
5 commits
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PCC status field exposes an error bit(2) to indicate any errors during
the execution of last comamnd. This patch checks the error bit before
notifying success/failure to the cpufreq driver.Signed-off-by: Prashanth Prakash
Signed-off-by: Rafael J. Wysocki -
The CPPC tables contain entries for per CPU feedback counters which
allows us to compute the delivered performance over a given interval
of time.The math for delivered performance per the CPPCv5.0+ spec is:
reference perf * delta(delivered perf ctr)/delta(ref perf ctr)Maintaining deltas of the counters in the kernel is messy, as it
depends on when the reads are triggered. (e.g. via the cpufreq
->get() interface). Also the ->get() interace only returns one
value, so cant return raw values. So instead, leave it to userspace
to keep track of raw values and do its math for CPUs it cares about.delivered and reference perf counters are exposed via the same
sysfs file to avoid the potential "skid", if these values are read
individually from userspace.Signed-off-by: Prashanth Prakash
Signed-off-by: Ashwin Chaugule
Signed-off-by: Rafael J. Wysocki -
Compute the expected transition latency for frequency transitions
using the values from the PCCT tables when the desired perf
register is in PCC.Signed-off-by: Prashanth Prakash
Reviewed-by: Alexey Klimov
Signed-off-by: Rafael J. Wysocki -
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
Signed-off-by: Rafael J. Wysocki -
For cases where sys mapped CPC registers need to be accessed
frequently, it helps immensly to pre-map them rather than map
and unmap for each operation. e.g. case where feedback counters
are sys mem map registers.Restructure cpc_read/write and the cpc_regs structure to allow
pre-mapping the system addresses and unmap them when the CPU exits.Signed-off-by: Ashwin Chaugule
Signed-off-by: Prashanth Prakash
Signed-off-by: Rafael J. Wysocki
25 Jun, 2016
1 commit
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Exports pcc_mbox_request_channel() and pcc_mbox_free_channel()
declarations into a pcc.h header file.Looks-good-to: Prashanth Prakash
Signed-off-by: Hoan Tran
Signed-off-by: Rafael J. Wysocki
03 Feb, 2016
1 commit
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Remove a redundant function declaration in cppc_acpi.h for
mbox_send_message(). That function is defined in mailbox_client.h,
which is already included.Signed-off-by: Timur Tabi
Signed-off-by: Rafael J. Wysocki
13 Oct, 2015
1 commit
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CPPC stands for Collaborative Processor Performance Controls
and is defined in the ACPI v5.0+ spec. It describes CPU
performance controls on an abstract and continuous scale
allowing the platform (e.g. remote power processor) to flexibly
optimize CPU performance with its knowledge of power budgets
and other architecture specific knowledge.This patch adds a shim which exports commonly used functions
to get and set CPPC specific controls for each CPU. This enables
CPUFreq drivers to gather per CPU performance data and use
with exisiting governors or even allows for customized governors
which are implemented inside CPUFreq drivers.Signed-off-by: Ashwin Chaugule
Reviewed-by: Al Stone
Signed-off-by: Rafael J. Wysocki