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ps: add -q/q/--quick-pid option

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This commit introduces a new option q/-q/--quick-pid
to the 'ps' command. The option does a similar job
to the p/-p/--pid option (i.e. selection of PIDs
listed in the comma separated list that follows
the option), but the new option is optimized
for speed.
In cases where users only need to specify a list
of PIDs to be shown and don't need other selection
options, forest type output and sorting options,
the new option is recommended as it decreases
the initial processing delay by avoiding reading
the necessary information from all the processes
running on the system and by simplifying
the internal filtering logic.
This commit is contained in:
Jaromir Capik
2014-07-10 21:14:02 +02:00
parent 6cd8691720
commit e751606fcc
6 changed files with 131 additions and 4 deletions
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75
ps/display.c
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@ -164,6 +164,7 @@ static void arg_show(void){
case SEL_FGID: show_gid("FGID", walk->n, walk->u); break;
case SEL_PGRP: show_pid("PGRP", walk->n, walk->u); break;
case SEL_PID : show_pid("PID ", walk->n, walk->u); break;
case SEL_PID_QUICK : show_pid("PID_QUICK ", walk->n, walk->u); break;
case SEL_PPID: show_pid("PPID", walk->n, walk->u); break;
case SEL_TTY : show_tty("TTY ", walk->n, walk->u); break;
case SEL_SESS: show_pid("SESS", walk->n, walk->u); break;
@ -343,8 +344,29 @@ static int want_this_proc_pcpu(proc_t *buf){
static void simple_spew(void){
static proc_t buf, buf2; // static avoids memset
PROCTAB* ptp;
pid_t* pidlist;
int flags;
int i;
ptp = openproc(needs_for_format | needs_for_sort | needs_for_select | needs_for_threads);
pidlist = NULL;
flags = needs_for_format | needs_for_sort | needs_for_select | needs_for_threads;
// -q option (only single SEL_PID_QUICK typecode entry expected in the list, if present)
if (selection_list && selection_list->typecode == SEL_PID_QUICK) {
flags |= PROC_PID;
pidlist = (pid_t*) malloc(selection_list->n * sizeof(pid_t));
if (!pidlist) {
fprintf(stderr, _("error: not enough memory\n"));
exit(1);
}
for (i = 0; i < selection_list->n; i++) {
pidlist[i] = selection_list->u[selection_list->n-i-1].pid;
}
}
ptp = openproc(flags, pidlist);
if(!ptp) {
fprintf(stderr, _("error: can not access /proc\n"));
exit(1);
@ -385,6 +407,8 @@ static void simple_spew(void){
break;
}
closeproc(ptp);
if (pidlist) free(pidlist);
}
/***** forest output requires sorting by ppid; add start_time by default */
@ -539,6 +563,52 @@ static void fancy_spew(void){
closeproc(ptp);
}
static void arg_check_conflicts(void)
{
int selection_list_len;
int has_quick_pid;
selection_node *walk = selection_list;
has_quick_pid = 0;
selection_list_len = 0;
while (walk) {
if (walk->typecode == SEL_PID_QUICK) has_quick_pid++;
walk = walk->next;
selection_list_len++;
}
/* -q doesn't allow multiple occurences */
if (has_quick_pid > 1) {
fprintf(stderr, "q/-q/--quick-pid can only be used once.\n");
exit(1);
}
/* -q doesn't allow combinations with other selection switches */
if (has_quick_pid && selection_list_len > has_quick_pid) {
fprintf(stderr, "q/-q/--quick-pid cannot be combined with other selection options.\n");
exit(1);
}
/* -q cannot be used with forest type listings */
if (has_quick_pid && forest_type) {
fprintf(stderr, "q/-q/--quick-pid cannot be used together with forest type listings.\n");
exit(1);
}
/* -q cannot be used with sort */
if (has_quick_pid && sort_list) {
fprintf(stderr, "q/-q,--quick-pid cannot be used together with sort options.\n");
exit(1);
}
/* -q cannot be used with -N */
if (has_quick_pid && negate_selection) {
fprintf(stderr, "q/-q/--quick-pid cannot be used together with negation switches.\n");
exit(1);
}
}
/***** no comment */
int main(int argc, char *argv[]){
@ -580,6 +650,9 @@ int main(int argc, char *argv[]){
reset_global(); /* must be before parser */
arg_parse(argc,argv);
/* check for invalid combination of arguments */
arg_check_conflicts();
/* arg_show(); */
trace("screen is %ux%u\n",screen_cols,screen_rows);
/* printf("sizeof(proc_t) is %d.\n", sizeof(proc_t)); */