mirror of
https://github.com/matrix-construct/construct
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55 lines
1.6 KiB
C++
55 lines
1.6 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_SYSCALL_TIMER_H
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namespace ircd::prof
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{
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struct syscall_timer;
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}
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/// This suite of devices is intended to figure out when a system call is
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/// really slow or "blocking." The original use-case is for io_submit() in
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/// fs::aio.
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///
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/// The sample is conducted with times(2) which is itself a system call
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/// though reasonably fast, and the result has poor resolution meaning
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/// the result of at() is generally 0 unless the system call was very slow.
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///
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/// It is started on construction. The user must later call sample()
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/// which returns the value of at() as well.
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struct ircd::prof::syscall_timer
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{
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struct high_resolution;
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uint64_t started, stopped;
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public:
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uint64_t at() const;
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uint64_t sample();
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syscall_timer() noexcept;
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};
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/// This is a higher resolution alternative. The sample may be conducted
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/// with getrusage() or perf events; the exact method is TBD and may be
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/// expensive/intrusive. This device should be used temporarily by developers
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/// and not left in place in committed code.
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struct ircd::prof::syscall_timer::high_resolution
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{
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uint64_t started, stopped;
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public:
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uint64_t at() const;
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uint64_t sample();
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high_resolution() noexcept;
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};
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