According to this paper Establishing a Base of Trust with Performance Counters for Enterprise Workloads
software randomization is not available in perf. "We program the PMU to sample with prime and non-prime periods. Due to perf limitations, software- based period randomization was unavailable, but the hardware randomizes the 4 least significant bits." 2015-09-09 17:16 GMT+02:00 Manuel Selva <[email protected]>: > Regarding perf mem record on Intel platforms, I think that the sampling > randomization is ensured by the hardware. > > ---- > Manu > > On 09/09/2015 05:11 PM, Milian Wolff wrote: >> >> Hey all, >> >> does perf randomize its sampling intervals/period to prevent pattern >> effects? >> I found https://lkml.org/lkml/2010/3/4/51 but neither the man page on perf >> record says anything on that matter, nor does the perf wiki say it's >> supported: >> >> https://perf.wiki.kernel.org/index.php/Tutorial#Period_and_rate >> >>> There is currently no support for sampling period randomization. >> >> >> So is it supported, or not? If it is supported, how do I enable it? Or is >> this >> enabled by default? >> >> If it is not supported, why so? Is it not important to have? >> >> Thanks >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-perf-users" > in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
