// Matrix Construct // // Copyright (C) Matrix Construct Developers, Authors & Contributors // Copyright (C) 2016-2018 Jason Volk // // Permission to use, copy, modify, and/or distribute this software for any // purpose with or without fee is hereby granted, provided that the above // copyright notice and this permission notice is present in all copies. The // full license for this software is available in the LICENSE file. #pragma once #define HAVE_IRCD_CTX_PROF_H /// Profiling for the context system. /// /// These facilities provide tools and statistics. The primary purpose here is /// to alert developers of unwanted context behavior, in addition to optimizing /// the overall performance of the context system. /// /// The original use case is for the embedded database backend. Function calls /// are made which may conduct blocking I/O before returning. This will hang the /// current userspace context while it is running and thus BLOCK EVERY CONTEXT /// in the entire IRCd. Since this is still an asynchronous system, it just /// doesn't have callbacks: we do not do I/O without a cooperative yield. /// Fortunately there are mechanisms to mitigate this -- but we have to know /// for sure. A database call which has been passed over for mitigation may /// start doing some blocking flush under load, etc. The profiler will alert /// us of this so it doesn't silently degrade performance. /// namespace ircd::ctx::prof { enum class event :uint8_t; struct ticker; uint64_t cycles() noexcept; string_view reflect(const event &); // totals const ticker &get() noexcept; const uint64_t &get(const event &); // specific context const ticker &get(const ctx &c) noexcept; const uint64_t &get(const ctx &c, const event &); // current slice state const ulong &cur_slice_start() noexcept; ulong cur_slice_cycles() noexcept; // test accessors bool slice_exceeded_warning(const ulong &cycles) noexcept; bool slice_exceeded_assertion(const ulong &cycles) noexcept; bool slice_exceeded_interrupt(const ulong &cycles) noexcept; bool stack_exceeded_warning(const size_t &size) noexcept; bool stack_exceeded_assertion(const size_t &size) noexcept; } namespace ircd::ctx::prof::settings { extern conf::item stack_usage_warning; // percentage extern conf::item stack_usage_assertion; // percentage extern conf::item slice_warning; // Warn when the yield-to-yield cycles exceeds extern conf::item slice_interrupt; // Interrupt exception when exceeded (not a signal) extern conf::item slice_assertion; // abort() when exceeded (not a signal, must yield) } /// Profiling events for marking. These are currently used internally at the /// appropriate point to mark(): the user of ircd::ctx has no reason to mark() /// these events; this interface is not quite developed for general use yet. enum class ircd::ctx::prof::event :uint8_t { SPAWN, // Context spawn requested JOIN, // Context join requested JOINED, // Context join completed ENTER, // Current context entered LEAVE, // Current context leaving YIELD, // Current context yielding CONTINUE, // Current context continuing INTERRUPT, // Current context detects interruption TERMINATE, // Current context detects termination CYCLES, // monotonic counter (rdtsc) _NUM_ }; /// structure aggregating any profiling related state for a ctx struct ircd::ctx::prof::ticker { // monotonic counters for events std::array()> event {{0}}; }; inline uint64_t ircd::ctx::prof::cur_slice_cycles() noexcept { return cycles() - cur_slice_start(); } extern inline uint64_t __attribute__((flatten, always_inline, gnu_inline, artificial)) ircd::ctx::prof::cycles() noexcept { return ircd::prof::cycles(); }