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* Copyright (c) 2015 Nicira, Inc.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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#ifndef __PERF_COUNTER_H
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#define __PERF_COUNTER_H 1
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* It is sometimes desirable to gain performance insights of a program
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* by using hardware counters. Recent Linux kernels started to support
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* a set of portable API for configuring and access those counter across
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* APIs provided by perf-counter.h provides a set of APIs that are
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* semi-integrated into OVS user spaces. The infrastructure that initializes,
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* cleanup, display and clear them at run time is provided. However the
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* sample points are not. A programmer needs insert sample points when needed.
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* Since there is no pre configured sample points, there is no run time
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* over head for the released product.
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* - Hard coded to sample CPU cycle count in user space only.
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* - Only one counter is sampled.
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* - Useful macros are only provided for function profiling.
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* - show and clear command applies to all counters, there is no way
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* to select a sub-set of counter.
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* Those are not fundamental limits, but only limited by current
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* Function instruction counter sample point Usage
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* ================================================
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* There are two macros provided:
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* Macro 'PERF_FUNCTON_COUNT_BEGIN' needs to be inserted towards the
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* beginning of the function where local variables are declared.
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* Macro 'PERF_FUNCTON_COUNT_END' needs to appear in the same function,
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* some where below 'PERF_FUNCTION_COUNT_BEGIN', usually towards of
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* int some_local_variable;
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* PERF_FUNCTION_COUNT_BEGIN;
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* PERF_FUNCTION_COUNT_END
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* This will maintain the number of times 'my_func()' is called, total
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* number of instructions '<implementation>' executed during all those calls.
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* Currently there are two limitation:
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* 1). At most one pair can appear in the same variable scope.
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* 2). The Macros use function name as the counter name for display.
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* Thus, all functions in one annotation session are required to
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* Note, there is no requirement for those macros to be balanced.
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* void my_func(int i){
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* PERF_FUNCTION_COUNT_BEGIN;
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* PERF_FUNCTION_COUNT_END;
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* will work just fine.
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#if defined(__linux__) && defined(HAVE_LINUX_PERF_EVENT_H)
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uint64_t total_count;
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#define PERF_COUNTER_ONCE_INITIALIZER(name) \
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void perf_counters_init(void);
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void perf_counters_destroy(void);
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void perf_counters_clear(void);
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uint64_t perf_counter_read(uint64_t *counter);
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void perf_counter_accumulate(struct perf_counter *counter,
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uint64_t start_count);
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char *perf_counters_to_string(void);
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/* User access macros. */
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#define PERF_FUNCTION_BEGIN \
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static struct perf_counter x__ = PERF_COUNTER_ONCE_INITIALIZER(__func__); \
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uint64_t start_count__ = perf_counter_read(&start_count__); \
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#define PERF_FUNCTION_END \
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perf_counter_accumulate(&x__, start_count__);
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#define PERF_FUNCTON_BEGIN
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#define PERF_FUNCTON_END
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static inline void perf_counters_init(void) {}
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static inline void perf_counters_destroy(void) {}
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static inline void perf_counters_clear(void) {}
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perf_counters_to_string(void)
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return xstrdup("Not Supported on this platform. Only available on Linux (version >= 2.6.32)");