forked from 0ad/0ad
Removes unused Windows sample-based custom profiler. Usage was removed in 56bd5b59b4
.
Differential Revision: https://code.wildfiregames.com/D5047 This was SVN commit r27712.
This commit is contained in:
parent
e4bcfd0556
commit
186bedae56
@ -1,242 +0,0 @@
|
||||
/* Copyright (C) 2010 Wildfire Games.
|
||||
*
|
||||
* Permission is hereby granted, free of charge, to any person obtaining
|
||||
* a copy of this software and associated documentation files (the
|
||||
* "Software"), to deal in the Software without restriction, including
|
||||
* without limitation the rights to use, copy, modify, merge, publish,
|
||||
* distribute, sublicense, and/or sell copies of the Software, and to
|
||||
* permit persons to whom the Software is furnished to do so, subject to
|
||||
* the following conditions:
|
||||
*
|
||||
* The above copyright notice and this permission notice shall be included
|
||||
* in all copies or substantial portions of the Software.
|
||||
*
|
||||
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
|
||||
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
|
||||
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
|
||||
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
|
||||
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
|
||||
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
|
||||
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
|
||||
*/
|
||||
|
||||
#include "precompiled.h"
|
||||
|
||||
#if 0
|
||||
|
||||
// we need a means of measuring performance, since it is hard to predict and
|
||||
// depends on many factors. to cover a wider range of configurations, this
|
||||
// must also be possible on end-user systems lacking specialized developer
|
||||
// tools. therefore, we must ship our own implementation; this complements
|
||||
// Intel VTune et al.
|
||||
//
|
||||
// there are 3 approaches to the problem:
|
||||
// - single-step analysis logs every executed instruction. very thorough, but
|
||||
// intolerably slow (~1000x) and not suitable for performance measurement.
|
||||
// - intrusive measuring tracks execution time of explicitly marked
|
||||
// functions or 'zones'. more complex, requires adding code, and
|
||||
// inaccurate when thread switches are frequent.
|
||||
// - IP sampling records the current instruction pointer at regular
|
||||
// intervals; slow sections of code will over time appear more often.
|
||||
// not exact, but simple and low-overhead.
|
||||
//
|
||||
// we implement IP sampling due to its simplicity. an intrusive approach
|
||||
// might also be added later to account for performance per-module
|
||||
// (helps spot the culprit in case hotspots are called from multiple sites).
|
||||
|
||||
|
||||
// on Windows, we retrieve the current IP with GetThreadContext. dox require
|
||||
// this to happen from another thread, and for the target to be suspended
|
||||
// (now enforced by XP SP2). this leads to all sorts of problems:
|
||||
// - if the suspended thread was dispatching an exception in the kernel,
|
||||
// register state may be a mix between the correct values and
|
||||
// those captured from the exception.
|
||||
// - if running on Win9x with real-mode drivers, interrupts may interfere
|
||||
// with GetThreadContext. however, it's not supported anyway due to other
|
||||
// deficiencies (e.g. lack of proper mmap support).
|
||||
// - the suspended thread may be holding locks; we need to be extremely
|
||||
// careful to avoid deadlock! many win api functions acquire locks in
|
||||
// non-obvious ways.
|
||||
|
||||
static HANDLE prof_target_thread;
|
||||
|
||||
static pthread_t prof_thread;
|
||||
|
||||
// delay [ms] between samples. OS sleep timers usually provide only
|
||||
// ms resolution. increasing interval reduces overhead and accuracy.
|
||||
static const int PROFILE_INTERVAL_MS = 1;
|
||||
|
||||
|
||||
static uintptr_t get_target_pc()
|
||||
{
|
||||
DWORD ret;
|
||||
HANDLE hThread = prof_target_thread; // convenience
|
||||
|
||||
ret = SuspendThread(hThread);
|
||||
if(ret == (DWORD)-1)
|
||||
{
|
||||
DEBUG_WARN_ERR(ERR::LOGIC); // get_target_pc: SuspendThread failed
|
||||
return 0;
|
||||
}
|
||||
// note: we don't need to call more than once: this increments a DWORD
|
||||
// 'suspend count'; target is guaranteed to be suspended unless
|
||||
// the function failed.
|
||||
|
||||
/////////////////////////////////////////////
|
||||
|
||||
// be VERY CAREFUL to avoid anything that may acquire a lock until
|
||||
// after ResumeThread! this includes locks taken by the OS,
|
||||
// e.g. malloc -> heap or GetProcAddress -> loader.
|
||||
// reason is, if the target thread was holding a lock we try to
|
||||
// acquire here, a classic deadlock results.
|
||||
|
||||
uintptr_t pc = 0; // => will return 0 if GetThreadContext fails
|
||||
|
||||
CONTEXT context;
|
||||
context.ContextFlags = CONTEXT_CONTROL;
|
||||
if(GetThreadContext(hThread, &context))
|
||||
pc = context.PC_;
|
||||
|
||||
/////////////////////////////////////////////
|
||||
|
||||
ret = ResumeThread(hThread);
|
||||
ENSURE(ret != 0);
|
||||
// don't fail (we have a valid PC), but warn
|
||||
|
||||
return pc;
|
||||
}
|
||||
|
||||
|
||||
static pthread_t thread;
|
||||
static sem_t exit_flag;
|
||||
|
||||
static void* prof_thread_func(void* UNUSED(data))
|
||||
{
|
||||
debug_SetThreadName("eip_sampler");
|
||||
|
||||
const long _1e6 = 1000000;
|
||||
const long _1e9 = 1000000000;
|
||||
|
||||
for(;;)
|
||||
{
|
||||
// calculate absolute timeout for sem_timedwait
|
||||
struct timespec abs_timeout;
|
||||
clock_gettime(CLOCK_REALTIME, &abs_timeout);
|
||||
abs_timeout.tv_nsec += PROFILE_INTERVAL_MS * _1e6;
|
||||
// .. handle nanosecond wraparound (must not be > 1000m)
|
||||
if(abs_timeout.tv_nsec >= _1e9)
|
||||
{
|
||||
abs_timeout.tv_nsec -= _1e9;
|
||||
abs_timeout.tv_sec++;
|
||||
}
|
||||
|
||||
errno = 0;
|
||||
// if we acquire the semaphore, exit was requested.
|
||||
if(sem_timedwait(&exit_flag, &abs_timeout) == 0)
|
||||
break;
|
||||
// actual error: warn
|
||||
if(errno != ETIMEDOUT)
|
||||
DEBUG_WARN_ERR(ERR::LOGIC); // wpcu prof_thread_func: sem_timedwait failed
|
||||
|
||||
uintptr_t pc = get_target_pc();
|
||||
UNUSED2(pc);
|
||||
|
||||
// ADD TO LIST
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
|
||||
// call from thread that is to be profiled
|
||||
Status prof_start()
|
||||
{
|
||||
// we need a real HANDLE to the target thread for use with
|
||||
// Suspend|ResumeThread and GetThreadContext.
|
||||
// alternative: DuplicateHandle on the current thread pseudo-HANDLE.
|
||||
// this way is a bit more obvious/simple.
|
||||
const DWORD access = THREAD_GET_CONTEXT|THREAD_SUSPEND_RESUME;
|
||||
HANDLE hThread = OpenThread(access, FALSE, GetCurrentThreadId());
|
||||
if(hThread == INVALID_HANDLE_VALUE)
|
||||
WARN_RETURN(ERR::FAIL);
|
||||
|
||||
prof_target_thread = hThread;
|
||||
|
||||
sem_init(&exit_flag, 0, 0);
|
||||
pthread_create(&thread, 0, prof_thread_func, 0);
|
||||
return INFO::OK;
|
||||
}
|
||||
|
||||
Status prof_shutdown()
|
||||
{
|
||||
WARN_IF_FALSE(CloseHandle(prof_target_thread));
|
||||
return INFO::OK;
|
||||
}
|
||||
|
||||
|
||||
|
||||
/*
|
||||
open question: how to store the EIP values returned? some background:
|
||||
the mechanism above churns out an EIP value (may be in our process, but might
|
||||
also be bogus); we need to store it somehow pending analysis.
|
||||
|
||||
when done with the current run, we'd want to resolve EIP -> function name,
|
||||
source file etc. (rather slow, so don't do it at runtime).
|
||||
|
||||
so, how to store it in the meantime? 2 possibilities:
|
||||
- simple array/vector of addresses (of course optimized to reduce allocs)
|
||||
- fixed size array of 'bins' (range of addresses; may be as fine as 1 byte);
|
||||
each bin has a counter which is incremented when the bin's corresponding
|
||||
address has been hit.
|
||||
|
||||
it's a size tradeoff here; for simple runs of < 1 min (60,000 ms), #1
|
||||
would use 240kb of mem. #2 requires sizeof_whole_program * bytes_per_counter
|
||||
up front, and has problems measuring DLLs (we'd have to explicitly map
|
||||
the DLL address range into a bin - ugh). however, if we ever want to
|
||||
test for say an hour (improves accuracy of profiling due to larger sample size),
|
||||
#1 would guzzle 15mb of memory.
|
||||
|
||||
hm, another idea would be to write out #1's list of addresses periodically.
|
||||
to make sure the disk I/O doesn't come at a bad time, we could have the main
|
||||
thread call into the profiler and request it write out at that time.
|
||||
this would require extreme caution to avoid the deadlock problem, but looks
|
||||
doable.
|
||||
|
||||
-------- [2] ----------
|
||||
|
||||
realistic profiler runs will take up to an hour.
|
||||
|
||||
writing out to disk would work: could have main thread call back.
|
||||
that and adding EIP to list would be atomic (locked).
|
||||
BUT: large amount of data, that's bad (loading at 30mb/s => 500ms load time alone)
|
||||
|
||||
problem with enumerating all symbols at startup: how do we enum all DLLs?
|
||||
|
||||
hybrid idea: std::map of EIPs. we don't build the map at startup,
|
||||
but add when first seen and subsequently increment counter stored there.
|
||||
problem: uses more memory/slower access than list.
|
||||
would have to make sure EIPs are reused.
|
||||
to help that, could quantize down to 4 byte (or so) bins.
|
||||
accessing debug information at runtime to determine function length is too slow.
|
||||
|
||||
maybe some weird data structure: one bucket controls say 256 bytes of code
|
||||
bucket is found by stripping off lower 8 bits. then, store only
|
||||
the hit count for that byte. where's the savings over normal count?
|
||||
|
||||
TODO: what if the thread is sleeping at the time we query EIP?
|
||||
can't detect that - suspend count is only set by SuspendThread
|
||||
do we want to report that point (it's good to know), or try to access other threads?
|
||||
|
||||
TODO split off target thread / get PC into sysdep; profiler thread is portable!
|
||||
|
||||
|
||||
at exit: resolve list to hotspots
|
||||
probably hard; a start would be just the function in which the address is, then hit count
|
||||
|
||||
|
||||
==========================================
|
||||
|
||||
|
||||
*/
|
||||
#endif
|
Loading…
Reference in New Issue
Block a user