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Optimize tabto()

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tabto is used in many lines of strace output.
On glibc, tprintf("%*s", col - curcol, "") is noticeably slow
compared to tprintf("                 "). Use the latter.
Observed ~15% reduction of time spent in userspace.

* defs.h: Drop extern declaration of acolumn. Make tabto()
take no parameters.
* process.c (sys_exit): Call tabto() with no parameters.
* syscall.c (trace_syscall_exiting): Call tabto() with no parameters.
* strace.c: Make acolumn static, add static char *acolumn_spaces.
(main): Allocate acolumn_spaces as a string of spaces.
(printleader): Call tabto() with no parameters.
(tabto): Use simpler method to print lots of spaces.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko 2011-08-25 01:27:59 +02:00
parent fabaa91ab6
commit 102ec49354
4 changed files with 18 additions and 10 deletions
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3
defs.h
View File

@ -564,7 +564,6 @@ extern int debug, followfork;
extern unsigned int ptrace_setoptions;
extern int dtime, xflag, qflag;
extern cflag_t cflag;
extern int acolumn;
extern int max_strlen;
extern struct tcb *tcp_last;
@ -639,7 +638,7 @@ extern void print_sigset(struct tcb *, long, int);
extern void printsignal(int);
extern void printleader(struct tcb *);
extern void printtrailer(void);
extern void tabto(int);
extern void tabto(void);
extern void call_summary(FILE *);
extern void tprint_iov(struct tcb *, unsigned long, unsigned long, int decode_iov);
extern void tprint_open_modes(mode_t);

2
process.c
View File

@ -429,7 +429,7 @@ sys_exit(struct tcb *tcp)
}
/* special case: we stop tracing this process, finish line now */
tprintf("%ld) ", tcp->u_arg[0]);
tabto(acolumn);
tabto();
tprintf("= ?");
printtrailer();
return 0;

19
strace.c
View File

@ -119,8 +119,9 @@ static char *username = NULL;
static uid_t run_uid;
static gid_t run_gid;
int acolumn = DEFAULT_ACOLUMN;
int max_strlen = DEFAULT_STRLEN;
static int acolumn = DEFAULT_ACOLUMN;
static char *acolumn_spaces;
static char *outfname = NULL;
static FILE *outf;
static int curcol;
@ -1033,6 +1034,8 @@ main(int argc, char *argv[])
break;
case 'a':
acolumn = atoi(optarg);
if (acolumn < 0)
error_msg_and_die("Bad column width '%s'", optarg);
break;
case 'e':
qualify(optarg);
@ -1086,6 +1089,12 @@ main(int argc, char *argv[])
}
}
acolumn_spaces = malloc(acolumn + 1);
if (!acolumn_spaces)
error_msg_and_die("Out of memory");
memset(acolumn_spaces, ' ', acolumn);
acolumn_spaces[acolumn] = '\0';
if ((optind == argc) == !pflag_seen)
usage(stderr, 1);
@ -2641,7 +2650,7 @@ printleader(struct tcb *tcp)
if (tcp_last->ptrace_errno) {
if (tcp_last->flags & TCB_INSYSCALL) {
tprintf(" <unavailable>) ");
tabto(acolumn);
tabto();
}
tprintf("= ? <unavailable>\n");
tcp_last->ptrace_errno = 0;
@ -2687,10 +2696,10 @@ printleader(struct tcb *tcp)
}
void
tabto(int col)
tabto(void)
{
if (curcol < col)
tprintf("%*s", col - curcol, "");
if (curcol < acolumn)
tprintf(acolumn_spaces + curcol);
}
void

4
syscall.c
View File

@ -2334,7 +2334,7 @@ trace_syscall_exiting(struct tcb *tcp)
if (res != 1) {
tprintf(") ");
tabto(acolumn);
tabto();
tprintf("= ? <unavailable>");
printtrailer();
tcp->flags &= ~TCB_INSYSCALL;
@ -2359,7 +2359,7 @@ trace_syscall_exiting(struct tcb *tcp)
}
tprintf(") ");
tabto(acolumn);
tabto();
u_error = tcp->u_error;
if (!SCNO_IN_RANGE(tcp->scno) ||
qual_flags[tcp->scno] & QUAL_RAW) {