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Subject: Re: svn commit: r274739 - head/sys/mips/conf
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From: Mark R V Murray <mark@grondar.org>
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References: <201411200552.sAK5qnXP063073@svn.freebsd.org>
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To: Warner Losh <imp@bsdimp.com>
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> On 24 Nov 2014, at 23:22, Warner Losh <imp@bsdimp.com> wrote:
>=20
> What=E2=80=99s the minimum specs required for get_cyclecount()? Not =
all of the
> boxes that Ian was posting about have high-resolution time-keeping =
counters
> in hardware=E2=80=A6 Maybe there=E2=80=99s some underlying expectation =
for this function
> that these systems either aren=E2=80=99t providing or can=E2=80=99t =
provide.

get_cyclecount should be a high-resolution timing counter linear in =
time, with a minimum tick no more accurate than a single instruction =
execution. In practice we take what we can get. It is used to measure =
hopefully chaotic events in order to obtain environmental entropy.

M
--=20
Mark R V Murray