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Add kernel support for context switch events

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These events only show if a thread has been removed from the CPU, but
doesn't provide information about what other thread caused the context
switch. This type of information can be obtained even with strict
/proc/sys/kernel/perf_event_paranoid settings.
This commit is contained in:
Rodrigo Arias 2021-11-16 15:08:27 +01:00 committed by Kevin Sala
parent 2961254838
commit ca95fb34a3
8 changed files with 244 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
CMakeLists.txt
View File

@ -80,6 +80,7 @@ add_executable(ovniemu
emu_ovni.c
emu_tampi.c
emu_nanos6.c
emu_kernel.c
trace.c
ovni.c
parson.c

43
cfg/cpu-kernel-context-switch.cfg Normal file
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@ -0,0 +1,43 @@
#ParaverCFG
ConfigFile.Version: 3.4
ConfigFile.NumWindows: 1
################################################################################
< NEW DISPLAYING WINDOW CPU: Context switches of the ACTIVE thread >
################################################################################
window_name CPU: Context switches of the ACTIVE thread
window_type single
window_id 1
window_position_x 960
window_position_y 287
window_width 954
window_height 236
window_comm_lines_enabled true
window_flags_enabled true
window_noncolor_mode true
window_logical_filtered true
window_physical_filtered false
window_comm_fromto true
window_comm_tagsize true
window_comm_typeval true
window_units Microseconds
window_maximum_y 5.000000000000
window_minimum_y 1.000000000000
window_compute_y_max true
window_level thread
window_scale_relative 1.000000000000
window_end_time_relative 1.000000000000
window_object appl { 1, { All } }
window_begin_time_relative 0.000000000000
window_open true
window_drawmode draw_maximum
window_drawmode_rows draw_maximum
window_pixel_size 1
window_labels_to_draw 1
window_selected_functions { 14, { {cpu, Active Thd}, {appl, Adding}, {task, Adding}, {thread, Last Evt Val}, {node, Adding}, {system, Adding}, {workload, Adding}, {from_obj, All}, {to_obj, All}, {tag_msg, All}, {size_msg, All}, {bw_msg, All}, {evt_type, =}, {evt_value, All} } }
window_compose_functions { 9, { {compose_cpu, As Is}, {compose_appl, As Is}, {compose_task, As Is}, {compose_thread, As Is}, {compose_node, As Is}, {compose_system, As Is}, {compose_workload, As Is}, {topcompose1, As Is}, {topcompose2, As Is} } }
window_filter_module evt_type 1 105
window_filter_module evt_type_label 1 "CPU: Context switches of the ACTIVE thread"
window_synchronize 1

43
cfg/thread-kernel-context-switch.cfg Normal file
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@ -0,0 +1,43 @@
#ParaverCFG
ConfigFile.Version: 3.4
ConfigFile.NumWindows: 1
################################################################################
< NEW DISPLAYING WINDOW Thread: Context switches of the CURRENT thread >
################################################################################
window_name Thread: Context switches of the CURRENT thread
window_type single
window_id 1
window_position_x 960
window_position_y 287
window_width 954
window_height 236
window_comm_lines_enabled true
window_flags_enabled true
window_noncolor_mode true
window_logical_filtered true
window_physical_filtered false
window_comm_fromto true
window_comm_tagsize true
window_comm_typeval true
window_units Microseconds
window_maximum_y 5.000000000000
window_minimum_y 1.000000000000
window_compute_y_max true
window_level thread
window_scale_relative 1.000000000000
window_end_time_relative 1.000000000000
window_object appl { 1, { All } }
window_begin_time_relative 0.000000000000
window_open true
window_drawmode draw_maximum
window_drawmode_rows draw_maximum
window_pixel_size 1
window_labels_to_draw 1
window_selected_functions { 14, { {cpu, Active Thd}, {appl, Adding}, {task, Adding}, {thread, Last Evt Val}, {node, Adding}, {system, Adding}, {workload, Adding}, {from_obj, All}, {to_obj, All}, {tag_msg, All}, {size_msg, All}, {bw_msg, All}, {evt_type, =}, {evt_value, All} } }
window_compose_functions { 9, { {compose_cpu, As Is}, {compose_appl, As Is}, {compose_task, As Is}, {compose_thread, As Is}, {compose_node, As Is}, {compose_system, As Is}, {compose_workload, As Is}, {topcompose1, As Is}, {topcompose2, As Is} } }
window_filter_module evt_type 1 55
window_filter_module evt_type_label 1 "Thread: Context switches of the CURRENT thread"
window_synchronize 1

4
doc/emu_events.txt
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@ -127,3 +127,7 @@ LS] Ends the submit of a task
LP[ Begins the spawn of a function
LP] Ends the spawn of a function
-------------------- Kernel (model=K) ----------------------
KCO Is out of the CPU due to a context switch
KCI Is back in the CPU due to a context switch

2
emu.c
View File

@ -266,6 +266,7 @@ hook_init(struct ovni_emu *emu)
hook_init_tampi(emu);
hook_init_openmp(emu);
hook_init_nanos6(emu);
hook_init_kernel(emu);
}
static void
@ -278,6 +279,7 @@ hook_pre(struct ovni_emu *emu)
case 'T': hook_pre_tampi(emu); break;
case 'M': hook_pre_openmp(emu); break;
case 'L': hook_pre_nanos6(emu); break;
case 'K': hook_pre_kernel(emu); break;
default:
break;
}

15
emu.h
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@ -99,6 +99,10 @@ enum nanos6_state {
ST_NANOS6_SPAWN = 8,
};
enum kernel_cs_state {
ST_KERNEL_CSOUT = 3,
};
struct ovni_ethread;
struct ovni_eproc;
@ -149,6 +153,8 @@ enum chan {
CHAN_OPENMP_MODE,
CHAN_NANOS6_SUBSYSTEM,
CHAN_KERNEL_CS,
CHAN_MAX
};
@ -170,6 +176,7 @@ enum chan_dirty {
/* Same order as `enum chan` */
static const int chan_to_prvtype[CHAN_MAX][3] = {
/* FIXME: Use odd/even identifiers for thread and cpu */
/* Channel TH CPU */
{ CHAN_OVNI_PID, 10, 60 },
{ CHAN_OVNI_TID, 11, 61 },
@ -178,17 +185,14 @@ static const int chan_to_prvtype[CHAN_MAX][3] = {
{ CHAN_OVNI_APPID, 14, 64 }, /* Not used */
{ CHAN_OVNI_CPU, 15, -1 },
{ CHAN_OVNI_FLUSH, 16, 66 },
{ CHAN_NOSV_TASKID, 20, 70 },
{ CHAN_NOSV_TYPEID, 21, 71 },
{ CHAN_NOSV_APPID, 22, 72 },
{ CHAN_NOSV_SUBSYSTEM, 23, 73 },
{ CHAN_TAMPI_MODE, 30, 80 },
{ CHAN_OPENMP_MODE, 40, 90 },
{ CHAN_NANOS6_SUBSYSTEM, 50, 100 },
{ CHAN_KERNEL_CS, 55, 105 },
};
#define CHAN_PRV_TH(id) chan_to_prvtype[id][CHAN_TH]
@ -493,6 +497,9 @@ void hook_pre_openmp(struct ovni_emu *emu);
void hook_init_nanos6(struct ovni_emu *emu);
void hook_pre_nanos6(struct ovni_emu *emu);
void hook_init_kernel(struct ovni_emu *emu);
void hook_pre_kernel(struct ovni_emu *emu);
struct ovni_cpu *emu_get_cpu(struct ovni_loom *loom, int cpuid);
struct ovni_ethread *emu_get_thread(struct ovni_eproc *proc, int tid);

102
emu_kernel.c Normal file
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@ -0,0 +1,102 @@
/*
* Copyright (c) 2021 Barcelona Supercomputing Center (BSC)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <assert.h>
#include "uthash.h"
#include "ovni.h"
#include "trace.h"
#include "emu.h"
#include "prv.h"
#include "chan.h"
/* --------------------------- init ------------------------------- */
void
hook_init_kernel(struct ovni_emu *emu)
{
struct ovni_ethread *th;
struct ovni_cpu *cpu;
size_t i;
int row;
FILE *prv_th, *prv_cpu;
int64_t *clock;
struct ovni_chan **uth, **ucpu;
clock = &emu->delta_time;
prv_th = emu->prv_thread;
prv_cpu = emu->prv_cpu;
/* Init the channels in all threads */
for(i=0; i<emu->total_nthreads; i++)
{
th = emu->global_thread[i];
row = th->gindex + 1;
uth = &emu->th_chan;
chan_th_init(th, uth, CHAN_KERNEL_CS, CHAN_TRACK_NONE, 0, 1, 1, row, prv_th, clock);
}
/* Init the channels in all cpus */
for(i=0; i<emu->total_ncpus; i++)
{
cpu = emu->global_cpu[i];
row = cpu->gindex + 1;
ucpu = &emu->cpu_chan;
chan_cpu_init(cpu, ucpu, CHAN_KERNEL_CS, CHAN_TRACK_TH_ACTIVE, 0, 0, 1, row, prv_cpu, clock);
}
}
/* --------------------------- pre ------------------------------- */
static void
context_switch(struct ovni_emu *emu)
{
struct ovni_ethread *th;
struct ovni_chan *chan;
th = emu->cur_thread;
chan = &th->chan[CHAN_KERNEL_CS];
switch(emu->cur_ev->header.value)
{
case 'O':
chan_push(chan, ST_KERNEL_CSOUT);
break;
case 'I':
chan_pop(chan, ST_KERNEL_CSOUT);
break;
default:
err("unexpected value '%c' (expecting 'O' or 'I')\n",
emu->cur_ev->header.value);
abort();
}
}
void
hook_pre_kernel(struct ovni_emu *emu)
{
assert(emu->cur_ev->header.model == 'K');
switch(emu->cur_ev->header.category)
{
case 'C': context_switch(emu); break;
default:
break;
}
}

23
pcf.c
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@ -383,6 +383,27 @@ static const struct event_type thread_nanos6_mode = {
nanos6_mode_values
};
/* ---------------- CHAN_KERNEL_CS ---------------- */
struct event_value kernel_cs_values[] = {
{ ST_NULL, "NULL" },
{ ST_TOO_MANY_TH, "Kernel CS: Unknown, multiple threads running" },
{ ST_KERNEL_CSOUT, "Context switch: Out of the CPU" },
{ -1, NULL },
};
struct event_type cpu_kernel_cs = {
0, CHAN_KERNEL_CS, CHAN_CPU,
"CPU: Context switches of the ACTIVE thread",
kernel_cs_values
};
struct event_type thread_kernel_cs = {
0, CHAN_KERNEL_CS, CHAN_TH,
"Thread: Context switches of the CURRENT thread",
kernel_cs_values
};
/* ----------------------------------------------- */
static void
@ -475,6 +496,7 @@ write_events(FILE *f, struct ovni_emu *emu)
write_event_type(f, &thread_tampi_mode);
write_event_type(f, &thread_openmp_mode);
write_event_type(f, &thread_nanos6_mode);
write_event_type(f, &thread_kernel_cs);
/* CPU */
write_event_type(f, &cpu_ovni_pid);
@ -491,6 +513,7 @@ write_events(FILE *f, struct ovni_emu *emu)
write_event_type(f, &cpu_tampi_mode);
write_event_type(f, &cpu_openmp_mode);
write_event_type(f, &cpu_nanos6_mode);
write_event_type(f, &cpu_kernel_cs);
/* Custom */
write_cpu_type(f, &thread_cpu_affinity, emu);