Date: Fri, 19 Nov 2010 17:45:31 +0200 From: Andriy Gapon <avg@freebsd.org> To: Daniel Nebdal <dnebdal@gmail.com> Cc: freebsd-acpi@freebsd.org, freebsd-current@freebsd.org Subject: Re: aperf/mperf Message-ID: <4CE69B9B.60101@freebsd.org> In-Reply-To: <AANLkTi=Tzxu--RAyqD2CQQWKCutCk%2B_8bFYSq1YsHno6@mail.gmail.com> References: <4CE29718.2050508@freebsd.org> <D1DB20AD-779E-469B-BFFA-C0BA1A249858@neville-neil.com> <4CE51CDA.6010202@freebsd.org> <AANLkTimcJFL8Y47mTznKz72w0z5%2BVoc9oWrz92kE%2BwQa@mail.gmail.com> <4CE533DE.7010401@freebsd.org> <4CE68C0B.1080007@freebsd.org> <AANLkTi=Tzxu--RAyqD2CQQWKCutCk%2B_8bFYSq1YsHno6@mail.gmail.com>
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[looks like I originally sent the reply only privately] on 19/11/2010 16:50 Daniel Nebdal said the following: > On Fri, Nov 19, 2010 at 4:39 PM, Andriy Gapon <avg@freebsd.org> 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. >> >> Ideas? >> Thanks! > > No comment on where to put it, but one other detail: Since these are > measures since last reset, you probably want a similar > "cpu_zero_a_m_perf" call. As for how that interacts with the sysctl, > uhm ... maybe also offering a time-since-last-reset could be useful? > I have something else in mind - no reset, but you call cpu_get_a_m_perf() twice, take differences in the counters (accounting for possible overflows) and divide those deltas. In my opinion that should work. -- Andriy Gapon
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