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Tag: rdtsc

__rdtscp calibration unstable under Linux on Intel Xeon X5550

I’m trying to use __rdtscp intrinsinc function to measure time intervals. Target platform is Linux x64, CPU Intel Xeon X5550. Although constant_tsc flag is set for this processor, calibrating __rdtscp gives very different results: As we can see the difference between program executions can be up to 3 times (125-360). Such instability is not appropriate for any measurements. Here is

rdtsc accuracy across CPU cores

I am sending network packets from one thread and receiving replies on a 2nd thread that runs on a different CPU core. My process measures the time between send & receive of each packet (similar to ping). I am using rdtsc for getting high-resolution, low-overhead timing, which is needed by my implementation. All measurments looks reliable. Still, I am worried

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