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-rw-r--r--README12
-rw-r--r--jitter/Makefile19
-rw-r--r--jitter/jitter.c303
3 files changed, 334 insertions, 0 deletions
diff --git a/README b/README
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+-------------------------------------------------------
+Performance Measurement and Analysis Tools (pma_tools)
+-------------------------------------------------------
+
+pma_tools will provide several useful scripts, micro-benchmarks to help
+characterize data plane performance.
+
+-------------------------------------------------------
+micro-benchmarks
+-------------------------------------------------------
+
+- jitter : A user space C program to assess OS level overhead.
diff --git a/jitter/Makefile b/jitter/Makefile
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+# Copyright (c) 2017 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+all:
+ gcc -O1 jitter.c -fstack-protector-all -fPIC -Wformat -Wformat-security -Wl,-z,noexecstack,-z,relro,-z,now -o jitter
+
+clean:
+ rm -f jitter
diff --git a/jitter/jitter.c b/jitter/jitter.c
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+++ b/jitter/jitter.c
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+/**
+ * Copyright (c) 2017 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Original Creation Date : Sept 1, 2012
+ * Last Modified : Dec 17, 2017
+ * Author: Shrikant M. Shah
+ * Contributor: Patrick Lu
+ *
+ * Program for measuring software jitter
+ *
+ * This program is meant for measuring the "jitter" in the execution time caused by OS and/or the underlying architecture.
+ * The program does the following:
+ * - Calls a dummy function which consists of a small piece of code block being executed in a loop. The loop count is user defined (default 80,000).
+ * - Measures the Execution time for this function in Core cycles
+ * - Compares the Execution time with Instantaneous Minimum and Maximum execution time values tracked during the display update interval. These values are adjusted based on the comparison.
+ * - Compares the execution time with Absolute Minimum and maximum execution values since the program started. These values are adjusted based on the comparison.
+ * - Repeats above operation.
+ * - Updates the display with the statistics once after the dummy function is executed certain number of times (default 20,000).
+ * The display update interval is approximately set to 1 second. At this time, Instantaneous Minimum and Maximum execution time are initialized.
+ * - The statistics include Instantaneous Minimum and Maximum execution times measured during the display interval and jitter.
+ * The most important statistic to watch is Inst_jitter, the difference between instantaneous Minimum and Maximum execution times
+ * Display update interval is also user programmable.
+ * Note that Absolute Minimum and Maximum execution times keep track of variations in the execution time over a long period of time.
+ * The Absolute Min and Max values can be reset using User signal.
+ *
+ */
+
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <signal.h>
+#include <string.h>
+
+union timestampclock
+{
+ uint64_t timestamp64;
+ struct
+ {
+ uint32_t low;
+ uint32_t high;
+ };
+}a;
+
+#define MINVAL 0xfffffffL
+
+int resetStats=0;
+unsigned int loopcount = 80000;
+unsigned int displayUpdate = 20000;
+#ifdef PROCESSOR_TRACE
+unsigned int jitter_threshold = 15000;
+#endif
+unsigned int iterations = 200;
+
+char *title = " Inst_Min Inst_Max Inst_jitter last_Exec Abs_min Abs_max tmp Interval Sample No\n";
+
+int dummyop(unsigned int loops, unsigned startval)
+{
+ register unsigned int i,a , k;
+ a = startval ;
+ k = loops;
+ for(i=0; i < k; i++)
+ {
+ a += (3*i + k);
+ a &=0x7f0f0000;
+ }
+
+ return a;
+}
+
+inline uint64_t TimeStampCounter()
+{
+ union timestampclock tscount;
+ uint32_t eax,edx;
+
+ __asm__ volatile("mfence");
+
+ __asm__ __volatile__("rdtsc" : "=a" (eax), "=d" (edx));
+ tscount.low = eax;
+ tscount.high = edx;
+ return tscount.timestamp64;
+}
+
+inline uint64_t TimeStampCounterEnd()
+{
+ union timestampclock tscount;
+ uint32_t eax,edx;
+
+ __asm__ __volatile__("rdtscp" : "=a" (eax), "=d" (edx)::"%rcx");
+ tscount.low = eax;
+ tscount.high = edx;
+ __asm__ __volatile__("rdtscp" : "=a" (eax), "=d" (edx)::"%rcx");
+ return tscount.timestamp64;
+}
+
+uint64_t clockdiff(uint64_t starttime,uint64_t endtime)
+{
+
+ uint64_t a ;
+ if (starttime > endtime)
+ a = starttime - endtime;
+ else
+ a = endtime - starttime;
+
+ return a ;
+}
+
+void signalHandler(int signalno)
+{
+ if (signalno == SIGUSR1)
+ {
+ printf("Resettings Absolute Min and Max counts\n");
+ resetStats = 1;
+ }
+}
+
+void showhelp()
+{
+ printf("usage:\n");
+ printf("taskset -c ./jitter [-l] [r] [-h] [-p $(pgrep perf)] [-t]\n");
+
+ printf(" -r : Display update rate. Default is %d\n", displayUpdate);
+ printf(" -l : Loop count for code block. Default is %d\n", loopcount);
+ printf(" -p : perf_pid [run: perf record -S -C$CORENO -e intel_pt// -v on another window]\n");
+#ifdef PROCESSOR_TRACE
+ printf(" -t : jitter threshold for perf trigger. Default is > %d cycles\n", jitter_threshold);
+#endif
+ printf(" -i : Sample counts after which program terminates. Default count is %u\n", iterations);
+ printf("For resetting statistics use: pkill -USR1 jitter\n");
+ printf("For elevating the priority of this program try: chrt -r -p 99 processId\n");
+
+}
+
+void displayInfo()
+{
+ printf("Timings are in CPU Core cycles\n");
+ printf("Inst_Min: Minimum Excution time during the display update interval(default is ~1 second)\n");
+ printf("Inst_Max: Maximum Excution time during the display update interval(default is ~1 second)\n");
+ printf("Inst_jitter: Jitter in the Excution time during rhe display update interval. This is the value of interest\n");
+ printf("last_Exec: The Excution time of last iteration just before the display update\n");
+ printf("Abs_Min: Absolute Minimum Excution time since the program started or statistics were reset\n");
+ printf("Abs_Max: Absolute Maximum Excution time since the program started or statistics were reset\n");
+ printf("tmp: Cumulative value calcualted by the dummy function\n");
+ printf("Interval: Time interval between the display updates in Core Cycles\n");
+ printf("Sample No: Sample number\n\n");
+}
+
+int main(int argc, char* argv[])
+{
+
+ register unsigned int tref=0;
+ register unsigned int SampleNo=0;
+ register long currentExectime;
+ uint64_t startTime,endTime,seedtime, lasttime;
+ uint64_t absoluteMin=MINVAL, absoluteMax=0, TransientMax=0, TransientMin=MINVAL;
+ unsigned int tmp=0;
+ int userinput;
+#ifdef PROCESSOR_TRACE
+ pid_t perf_pid = -1;
+ int skip = 5, signaled = 0;
+#endif
+
+ printf("Linux Jitter testing program version 1.8\n");
+
+ while ((userinput = getopt(argc, argv, "l:r:hp:t:i:")) != EOF)
+ {
+ switch(userinput)
+ {
+ case 'h' : showhelp();
+ exit(0);
+ case 'l' : loopcount = strtoul(optarg, (char**)NULL, 0);
+ break;
+ case 'r' : displayUpdate = strtoul(optarg, (char**)NULL, 0);
+ break;
+ case 'p' :
+#ifdef PROCESSOR_TRACE
+ perf_pid = strtol(optarg, (char**)NULL, 0);
+ printf("Perf PID=%d\n", perf_pid);
+#else
+ printf("jitter program did not compile with -DPROCESSOR_TRACE, cannot use Linux perf with Intel Processor Trace to record jitter source\n");
+#endif
+ break;
+
+ case 'i' :
+ iterations = strtoul(optarg, (char**)NULL, 0);
+ printf("Iterations=%u\n", iterations);
+ break;
+
+ case 't' :
+#ifdef PROCESSOR_TRACE
+ jitter_threshold = strtoul(optarg, (char**)NULL, 0);
+ printf("Update jitter threshold to %u\n", jitter_threshold);
+#else
+ printf("jitter program did not compile with -DPROCESSOR_TRACE, cannot use Linux perf with Intel Processor Trace to record jitter source\n");
+#endif
+ break;
+ }
+ }
+
+ printf("The pragram will execute a dummy function %u times\n",loopcount);
+ printf("Display is updated every %u displayUpdate intervals\n",displayUpdate);
+
+ displayInfo();
+
+ // register signal handler for resetting Absoulte statistics
+ if (signal(SIGUSR1, signalHandler) == SIG_ERR)
+ {
+ printf("**** Error: Signal Handler is somehow not registered. Sorry, you cannot reset statistics using USR1 signal\n");
+
+ }
+
+ printf("%s",title);
+
+ seedtime = TimeStampCounter(); // get a random value from timestamp
+
+ // prime the cache by executing the code a few times
+ for(SampleNo =0;SampleNo < 1000; SampleNo++)
+ {
+ tmp += dummyop(loopcount, (uint32_t) seedtime);
+ }
+
+ SampleNo = 0;
+ tref =0;
+
+ do // run the loop for a long time
+ {
+
+ startTime = TimeStampCounter(); // timestamp start
+ tmp += dummyop(loopcount, (uint32_t) seedtime); // run the compute function 'loopcount' times
+ endTime = TimeStampCounterEnd(); // timestamp end
+
+ currentExectime = clockdiff(startTime, endTime); // calculate differnce in clocks
+
+ // calcualte absolute min and max
+ if (currentExectime < absoluteMin) // calculate absolute min
+ absoluteMin = currentExectime;
+ if (currentExectime>= absoluteMax) // calculate absolute max
+ absoluteMax = currentExectime;
+
+ // calcualte Max execution time within the Display displayUpdate interval
+ if (currentExectime < TransientMin)
+ TransientMin = currentExectime; // temporary min
+ if (currentExectime >= TransientMax)
+ TransientMax = currentExectime; // temporary max
+
+#ifdef PROCESSOR_TRACE
+ if ((perf_pid != -1) && (SampleNo > skip) && !(signaled) && (currentExectime - TransientMin) > jitter_threshold) {
+ kill(perf_pid, SIGUSR2);
+ signaled = 1;
+ }
+#endif
+
+ if(tref++ >= displayUpdate) // update the stats on screen/memory at displayUpdate interval
+ {
+ tref=1;
+ if(SampleNo > 0)
+ printf("%10lu %10lu %10lu %10lu %10lu %10lu %13u %10lu %10u\n",
+ TransientMin,
+ TransientMax,
+ TransientMax-TransientMin,
+ currentExectime, absoluteMin,
+ absoluteMax,tmp,
+ (endTime-lasttime),
+ SampleNo);
+
+ SampleNo++;
+ lasttime = endTime;
+
+ TransientMax = 0; // reset TransientMax to zero
+ TransientMin = MINVAL;
+
+ if (resetStats !=0) // the varibale is set if user issues 'pkill USR1 jitter' signal
+ {
+ absoluteMax = 0;
+ absoluteMin = MINVAL;
+ resetStats = 0;
+ SampleNo = 1 ;
+#ifdef PROCESSOR_TRACE
+ signaled = 0;
+#endif
+ }
+
+
+ if (!(SampleNo % 40)) // print the title every 40 lines
+ printf("%s",title);
+
+ }
+
+ } while(SampleNo <= iterations);
+
+}