on 19/11/2010 21:08 Nate Lawson said the following: > On 11/19/2010 6:39 AM, Andriy Gapon wrote: >> >> I am thinking about providing two APIs for this. >> >> 1. KPI >> void cpu_get_a_m_perf(u_int cpu, uint64_t *aperf, uint64_t *mperf); >> >> 2. Userland >> sysctl dev.cpu.N.aperf_mperf that returns two UQUAD values. >> >> But I am not sure where to put the code for both APIs. >> Adding another device under cpu seems like an overkill. > > These can be exported as a common interface from cpufreq > (dev,cpu.X.perf_stats) and supplied by the child acpi_perf driver on > each cpu.
This suggestion sounds quite appealing. But I have some concerns. What if hardware has the capability, but there is no cpufreq - could these MSRs be still useful? Or are they useful only with cpufreq? Probably the latter... Then, another exotic case - if a driver like est or hwpstate is attached "directly", i.e. there is no acpi_perf/_PSS - would the MSRs be still useful? Not sure. -- Andriy Gapon _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
