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give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
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Escape single quotes in literal strings from groff's Unicode transform.
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Fear. Run. Save yourself. No user-serviceable parts.
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Title "OPENSSL_INSTRUMENT_BUS 3"
way too many mistakes in technical documents.
Standard preamble:
========================================================================
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.... Set up some character translations and predefined strings. \*(-- will
give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
double quote, and \*(R" will give a right double quote. \*(C+ will
give a nicer C++. Capital omega is used to do unbreakable dashes and
therefore won't be available. \*(C` and \*(C' expand to `' in nroff,
nothing in troff, for use with C<>.
.tr \(*W- . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' . ds C` . ds C' 'br\}
Escape single quotes in literal strings from groff's Unicode transform.
If the F register is >0, we'll generate index entries on stderr for
titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
entries marked with X<> in POD. Of course, you'll have to process the
output yourself in some meaningful fashion.
Avoid warning from groff about undefined register 'F'.
.. .nr rF 0 . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF
Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
Fear. Run. Save yourself. No user-serviceable parts.
. \" fudge factors for nroff and troff . ds #H 0 . ds #V .8m . ds #F .3m . ds #[ \f1 . ds #] .\} . ds #H ((1u-(\\\\n(.fu%2u))*.13m) . ds #V .6m . ds #F 0 . ds #[ \& . ds #] \& .\} . \" simple accents for nroff and troff . ds ' \& . ds ` \& . ds ^ \& . ds , \& . ds ~ ~ . ds / .\} . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' .\} . \" troff and (daisy-wheel) nroff accents . \" corrections for vroff . \" for low resolution devices (crt and lpr) \{\ . ds : e . ds 8 ss . ds o a . ds d- d\h'-1'\(ga . ds D- D\h'-1'\(hy . ds th \o'bp' . ds Th \o'LP' . ds ae ae . ds Ae AE .\} ========================================================================
Title "OPENSSL_INSTRUMENT_BUS 3"
OPENSSL_INSTRUMENT_BUS 3 "2022-05-03" "1.1.1o" "OpenSSL"
For nroff, turn off justification. Always turn off hyphenation; it makesway too many mistakes in technical documents.
"NAME"
OPENSSL_instrument_bus, OPENSSL_instrument_bus2 - instrument references to memory bus
"SYNOPSIS"
Header "SYNOPSIS" .Vb 4
#ifdef OPENSSL_CPUID_OBJ
size_t OPENSSL_instrument_bus(int *vector, size_t num);
size_t OPENSSL_instrument_bus2(int *vector, size_t num, size_t max);
#endif
.Ve
"DESCRIPTION"
Header "DESCRIPTION" It was empirically found that timings of references to primary memory
are subject to irregular, apparently non-deterministic variations. The
subroutines in question instrument these references for purposes of
gathering randomness for random number generator. In order to make it
bus-bound a 'flush cache line' instruction is used between probes. In
addition probes are added to vector elements in atomic or
interlocked manner, which should contribute additional noise on
multi-processor systems. This also means that vector[num] should be
zeroed upon invocation (if you want to retrieve actual probe values).
\fBOPENSSL_instrument_bus() performs num probes and records the number of oscillator cycles every probe took.
\fBOPENSSL_instrument_bus2() on the other hand accumulates consecutive probes with the same value, i.e. in a way it records duration of periods when probe values appeared deterministic. The subroutine performs at most max probes in attempt to fill the vector[num], with max value of 0 meaning \*(L"as many as it takes.\*(R"
"RETURN VALUES"
Header "RETURN VALUES" Return value of 0 indicates that \s-1CPU\s0 is not capable of performing the
benchmark, either because oscillator counter or 'flush cache line' is
not available on current platform. For reference, on x86 'flush cache
line' was introduced with the \s-1SSE2\s0 extensions.
Otherwise number of recorded values is returned.
"COPYRIGHT"
Header "COPYRIGHT" Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.