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construct/include/ircd/ctx/prof.h

73 lines
3.1 KiB
C++

/*
* charybdis: oh just a little chat server
*
* Copyright (C) 2016 Charybdis Development Team
* Copyright (C) 2016 Jason Volk <jason@zemos.net>
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#define HAVE_IRCD_CTX_PROF_H
namespace ircd::ctx
{
size_t stack_usage_here(const ctx &) __attribute__((noinline));
size_t stack_usage_here() __attribute__((noinline));
}
/* 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;
struct settings extern settings;
void mark(const event &);
}
enum class ircd::ctx::prof::event
{
SPAWN, // Context spawn requested
JOIN, // Context join requested
JOINED, // Context join completed
CUR_ENTER, // Current context entered
CUR_LEAVE, // Current context leaving
CUR_YIELD, // Current context yielding
CUR_CONTINUE, // Current context continuing
CUR_INTERRUPT, // Current context detects interruption
};
struct ircd::ctx::prof::settings
{
double stack_usage_warning; // percentage
double stack_usage_assertion; // percentage
microseconds slice_warning; // Warn when the yield-to-yield time exceeds
microseconds slice_interrupt; // Interrupt exception when exceeded (not a signal)
microseconds slice_assertion; // abort() when exceeded (not a signal, must yield)
};