minix/lib/libsys/profile.c

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/*
* profile.c - library functions for call profiling
*
* For processes that were compiled using ACK with the -Rcem-p option,
* procentry and procexit will be called on entry and exit of their
* functions. Procentry/procexit are implemented here as generic library
* functions.
*
* Changes:
* 14 Aug, 2006 Created (Rogier Meurs)
*/
#include <lib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <minix/profile.h>
#include <minix/sysutil.h>
#include <minix/u64.h>
PRIVATE char cpath[CPROF_CPATH_MAX_LEN]; /* current call path string */
PRIVATE int cpath_len; /* current call path len */
PRIVATE struct cprof_tbl_s *cprof_slot; /* slot of current function */
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struct stack_s { /* stack entry */
int cpath_len; /* call path len */
struct cprof_tbl_s *slot; /* table slot */
u64_t start_1; /* count @ begin of procentry */
u64_t start_2; /* count @ end of procentry */
u64_t spent_deeper; /* spent in called functions */
};
PRIVATE struct stack_s cprof_stk[CPROF_STACK_SIZE]; /* stack */
PRIVATE int cprof_stk_top; /* top of stack */
EXTERN struct cprof_tbl_s cprof_tbl[]; /* hash table */
PRIVATE int cprof_tbl_size; /* nr of slots */
PRIVATE struct cprof_tbl_s *idx[CPROF_INDEX_SIZE]; /* index to table */
PRIVATE struct cprof_ctl_s control; /* for comms with kernel */
PRIVATE int cprof_announce; /* announce on n-th execution
* of procentry */
PRIVATE int cprof_locked; /* for reentrancy */
FORWARD _PROTOTYPE(void cprof_init, (void) );
FORWARD _PROTOTYPE(void reset, (void) );
FORWARD _PROTOTYPE(void clear_tbl, (void) );
PUBLIC void procentry (char *name)
{
static int init = 0;
unsigned hash = 0, x = 0;
int i = 0;
struct cprof_tbl_s *last;
char c;
u64_t start;
/* Procentry is not reentrant. */
if (cprof_locked) return; else cprof_locked = 1;
/* Read CPU cycle count into local variable. */
read_tsc_64(&start);
/* Run init code once after system boot. */
if (init == 0) {
cprof_init();
init++;
}
/* Announce once. */
if (init > -1 && init++ == cprof_announce) {
/* Tell kernel about control structure and table locations.
*
* In userspace processes, the library function profile_register
* will be used. This function does a kernel call (sys_profbuf) to
* announce to the kernel the location of the control struct and
* hash table. The control struct is used by the kernel to write
* a flag if resetting of the table is requested. The location of
* the table is needed to copy the information to the user process
* that requests it.
*
* Kernelspace processes don't use the library function but have
* their own implemention that executes logic similar to sys_profbuf.
* The reason for this is that the kernel is non-reentrant, therefore
* a kernelspace process is not able to do a kernel call itself since
* this would cause a deadlock.
*/
profile_register((void *) &control, (void *) &cprof_tbl);
init = -1;
}
/* Only continue if sane. */
if (control.err) return;
/* Check if kernel instructed to reset profiling data. */
if (control.reset) reset();
/* Increase stack. */
if (++cprof_stk_top == CPROF_STACK_SIZE) {
printf("CPROFILE error: stack overrun\n");
control.err |= CPROF_STACK_OVERRUN;
return;
}
/* Save initial cycle count on stack. */
cprof_stk[cprof_stk_top].start_1 = start;
/* Check available call path len. */
if (cpath_len + strlen(name) + 1 > CPROF_CPATH_MAX_LEN) {
printf("CPROFILE error: call path overrun\n");
control.err |= CPROF_CPATH_OVERRUN;
return;
}
/* Save previous call path length on stack. */
cprof_stk[cprof_stk_top].cpath_len = cpath_len;
/* Generate new call path string and length.*/
if (cprof_stk_top > 0) /* Path is space separated. */
cpath[cpath_len++] = ' ';
while ((c = *(name++)) != '\0') /* Append function name. */
cpath[cpath_len++] = c;
cpath[cpath_len] = '\0'; /* Null-termination. */
/* Calculate hash for call path string (algorithm: ELF). */
for (i=0; i<cpath_len; i++) {
hash = (hash << 4) + cpath[i];
if ((x = hash & 0xF0000000L) != 0) {
hash ^= (x >> 24);
hash &= ~x;
}
}
hash %= CPROF_INDEX_SIZE;
/* Look up the slot for this call path in the hash table. */
for (cprof_slot = idx[hash]; cprof_slot != 0; cprof_slot = cprof_slot->next)
if (strcmp(cprof_slot->cpath, cpath) == 0) break;
if (cprof_slot)
cprof_slot->calls++; /* found slot: update call counter */
else {
/* Not found: insert path into hash table. */
if (control.slots_used == cprof_tbl_size) {
printf("CPROFILE error: table overrun\n");
control.err |= CPROF_TABLE_OVERRUN;
return;
}
/* Set values for new slot. */
cprof_slot = &cprof_tbl[control.slots_used++];
strcpy(cprof_slot->cpath, cpath);
cprof_slot->calls = 1;
/* Update index. */
if (idx[hash] == 0) {
/* No collision: simple update. */
idx[hash] = cprof_slot;
} else {
/* Collision: update last in chain. */
for (last = idx[hash]; last->next != 0; last = last->next);
last->next = cprof_slot;
}
}
/* Save slot on stack. */
cprof_stk[cprof_stk_top].slot = cprof_slot;
/* Again save CPU cycle count on stack. */
read_tsc_64(&cprof_stk[cprof_stk_top].start_2);
cprof_locked = 0;
}
PUBLIC void procexit (char *UNUSED(name))
{
u64_t stop, spent;
u32_t tsc_lo, tsc_hi;
/* Procexit is not reentrant. */
if (cprof_locked) return; else cprof_locked = 1;
/* First thing: read CPU cycle count into local variable. */
read_tsc(&tsc_hi, &tsc_lo);
stop = make64(tsc_lo, tsc_hi);
/* Only continue if sane. */
if (control.err) return;
/* Update cycle count for this call path. Exclude time spent in procentry/
* procexit by using measurements taken at end of procentry and begin of
* procexit (the "small" difference). This way, only the call overhead for
* the procentry/procexit functions will be attributed to this call path,
* not the procentry/procexit cycles.
*/
/* Calculate "small" difference. */
spent = sub64(stop, cprof_stk[cprof_stk_top].start_2);
cprof_stk[cprof_stk_top].slot->cycles =
add64(cprof_stk[cprof_stk_top].slot->cycles,
sub64(spent, cprof_stk[cprof_stk_top].spent_deeper));
/* Clear spent_deeper for call level we're leaving. */
cprof_stk[cprof_stk_top].spent_deeper = cvu64(0);
/* Adjust call path string and stack. */
cpath_len = cprof_stk[cprof_stk_top].cpath_len;
cpath[cpath_len] = '\0';
/* Update spent_deeper for call level below. Include time spent in
* procentry/procexit by using measurements taken at begin of procentry
* and end of procexit (the "big" difference). This way the time spent in
* procentry/procexit will be included in spent_deeper and therefore, since
* this value is substracted from the lower call level, it will not be
* attributed to any call path. This way, pollution of the statistics
* because of procentry/procexit is kept to a minimum.
*/
/* Read CPU cycle count. */
read_tsc(&tsc_hi, &tsc_lo);
stop = make64(tsc_lo, tsc_hi);
/* Calculate "big" difference. */
spent = sub64(stop, cprof_stk[cprof_stk_top].start_1);
cprof_stk_top--; /* decrease stack */
if (cprof_stk_top >= 0) /* don't update non-existent level -1 */
cprof_stk[cprof_stk_top].spent_deeper =
add64(cprof_stk[cprof_stk_top].spent_deeper, spent);
cprof_locked = 0;
}
PRIVATE void cprof_init()
{
int i;
cpath[0] = '\0';
cpath_len = 0;
cprof_stk_top = -1;
control.reset = 0;
control.err = 0;
cprof_tbl_size = profile_get_tbl_size();
cprof_announce = profile_get_announce();
clear_tbl();
for (i=0; i<CPROF_STACK_SIZE; i++) {
cprof_stk[i].cpath_len = 0;
cprof_stk[i].slot = 0;
cprof_stk[i].start_1 = cvu64(0);
cprof_stk[i].start_2 = cvu64(0);
cprof_stk[i].spent_deeper = cvu64(0);
}
}
PRIVATE void reset()
{
clear_tbl();
control.reset = 0;
}
PRIVATE void clear_tbl()
{
int i;
/* Reset profiling table. */
control.slots_used = 0;
for (i=0; i<CPROF_INDEX_SIZE; i++) idx[i] = 0; /* clear index */
for (i=0; i<cprof_tbl_size; i++) { /* clear table */
memset(cprof_tbl[i].cpath, '\0', CPROF_CPATH_MAX_LEN);
cprof_tbl[i].next = 0;
cprof_tbl[i].calls = 0;
cprof_tbl[i].cycles = make64(0, 0);
}
}