xemu/include/qemu/qsp.h

/*
 * qsp.c - QEMU Synchronization Profiler
 *
 * Copyright (C) 2018, Emilio G. Cota <cota@braap.org>
 *
 * License: GNU GPL, version 2 or later.
 *   See the COPYING file in the top-level directory.
 *
 * Note: this header file can *only* be included from thread.h.
 */
#ifndef QEMU_QSP_H
#define QEMU_QSP_H

#include "qemu/fprintf-fn.h"

enum QSPSortBy {
    QSP_SORT_BY_TOTAL_WAIT_TIME,
    QSP_SORT_BY_AVG_WAIT_TIME,
};

void qsp_report(FILE *f, fprintf_function cpu_fprintf, size_t max,
                enum QSPSortBy sort_by);

bool qsp_is_enabled(void);
void qsp_enable(void);
void qsp_disable(void);

#endif /* QEMU_QSP_H */
qsp: QEMU's Synchronization Profiler The goal of this module is to profile synchronization primitives (i.e. mutexes, recursive mutexes and condition variables) so that scalability issues can be quickly diagnosed. Sync primitives are profiled by QSP based on the vaddr of the object accessed as well as the call site (file:line_nr). That means the same object called from two different call sites will be tracked in separate entries, which might be reported together or separately (see subsequent commit on call site coalescing). Some perf numbers: Host: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz Command: taskset -c 0 tests/atomic_add-bench -d 5 -m - Before: 54.80 Mops/s - After: 54.75 Mops/s That is, a negligible slowdown due to the now indirect call to qemu_mutex_lock. Note that using a branch instead of an indirect call introduces a more severe slowdown (53.65 Mops/s, i.e. 2% slowdown). Enabling the profiler (with -p, added in this series) is more interesting: - No profiling: 54.75 Mops/s - W/ profiling: 12.53 Mops/s That is, a 4.36X slowdown. We can break down this slowdown by removing the get_clock calls or the entry lookup: - No profiling: 54.75 Mops/s - W/o get_clock: 25.37 Mops/s - W/o entry lookup: 19.30 Mops/s - W/ profiling: 12.53 Mops/s Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> 2017-08-08 17:53:15 +00:00			`/*`
			`* qsp.c - QEMU Synchronization Profiler`
			`*`
			`* Copyright (C) 2018, Emilio G. Cota <cota@braap.org>`
			`*`
			`* License: GNU GPL, version 2 or later.`
			`* See the COPYING file in the top-level directory.`
			`*`
			`* Note: this header file can only be included from thread.h.`
			`*/`
			`#ifndef QEMU_QSP_H`
			`#define QEMU_QSP_H`

			`#include "qemu/fprintf-fn.h"`

qsp: add sort_by option to qsp_report Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> 2018-08-17 03:14:40 +00:00			`enum QSPSortBy {`
			`QSP_SORT_BY_TOTAL_WAIT_TIME,`
			`QSP_SORT_BY_AVG_WAIT_TIME,`
			`};`

			`void qsp_report(FILE *f, fprintf_function cpu_fprintf, size_t max,`
			`enum QSPSortBy sort_by);`
qsp: QEMU's Synchronization Profiler The goal of this module is to profile synchronization primitives (i.e. mutexes, recursive mutexes and condition variables) so that scalability issues can be quickly diagnosed. Sync primitives are profiled by QSP based on the vaddr of the object accessed as well as the call site (file:line_nr). That means the same object called from two different call sites will be tracked in separate entries, which might be reported together or separately (see subsequent commit on call site coalescing). Some perf numbers: Host: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz Command: taskset -c 0 tests/atomic_add-bench -d 5 -m - Before: 54.80 Mops/s - After: 54.75 Mops/s That is, a negligible slowdown due to the now indirect call to qemu_mutex_lock. Note that using a branch instead of an indirect call introduces a more severe slowdown (53.65 Mops/s, i.e. 2% slowdown). Enabling the profiler (with -p, added in this series) is more interesting: - No profiling: 54.75 Mops/s - W/ profiling: 12.53 Mops/s That is, a 4.36X slowdown. We can break down this slowdown by removing the get_clock calls or the entry lookup: - No profiling: 54.75 Mops/s - W/o get_clock: 25.37 Mops/s - W/o entry lookup: 19.30 Mops/s - W/ profiling: 12.53 Mops/s Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> 2017-08-08 17:53:15 +00:00
			`bool qsp_is_enabled(void);`
			`void qsp_enable(void);`
			`void qsp_disable(void);`

			`#endif /* QEMU_QSP_H */`