mirror of
https://github.com/matrix-construct/construct
synced 2024-11-30 02:32:43 +01:00
97 lines
2.3 KiB
C++
97 lines
2.3 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_PROF_SCOPE_CYCLES_H
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namespace ircd::prof
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{
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template<bool fenced = false>
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struct scope_cycles;
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}
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/// Count the reference cycles for a scope using the lifetime of this object.
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/// The result is added to the value in `result`; note that result must be
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/// initialized.
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///
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/// The 'fenced' option in the template enables fence instructions as
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/// prescribed by amd64 manuals. The fences provide a more accurate result for
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/// the section being counted at the cost of additional general overhead. This
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/// is disabled by default so that permanent instances of this device are not
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/// interfering and don't require any templating.
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///
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template<bool fenced>
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struct ircd::prof::scope_cycles
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{
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uint64_t &result;
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uint64_t started;
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scope_cycles(uint64_t &result) noexcept;
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scope_cycles(const scope_cycles &) = delete;
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~scope_cycles() noexcept;
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};
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template<bool fenced>
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#ifdef __clang__
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inline //TODO: ???
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#else
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extern inline
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__attribute__((always_inline, gnu_inline, artificial))
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#endif
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ircd::prof::scope_cycles<fenced>::scope_cycles(uint64_t &result)
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noexcept
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:result{result}
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{
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if constexpr(fenced)
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{
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#if defined(__x86_64__) || defined(__i386__)
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asm volatile ("mfence");
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asm volatile ("lfence");
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#endif
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}
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started = cycles();
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if constexpr(fenced)
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{
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#if defined(__x86_64__) || defined(__i386__)
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asm volatile ("lfence");
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#endif
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}
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}
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template<bool fenced>
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#ifdef __clang__
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inline //TODO: ???
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#else
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extern inline
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__attribute__((always_inline, gnu_inline, artificial))
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#endif
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ircd::prof::scope_cycles<fenced>::~scope_cycles()
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noexcept
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{
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if constexpr(fenced)
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{
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#if defined(__x86_64__) || defined(__i386__)
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asm volatile ("mfence");
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asm volatile ("lfence");
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#endif
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}
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const uint64_t stopped(cycles());
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result += stopped - started;
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if constexpr(fenced)
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{
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#if defined(__x86_64__) || defined(__i386__)
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asm volatile ("lfence");
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#endif
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}
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}
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