Re: iostat(8): implement periodic display with setitimer(2)
On Wed, 28 Dec 2022 11:15:50 -0500, Scott Cheloha wrote: > Neither are arbitrary. > > The current maximum of one hundred million seconds is based on the old > nanosleep(2) limit prior to the 6.5 release. It was a documented > limit; see the manpage from the 6.4 release: > > http://man.openbsd.org/OpenBSD-6.4/nanosleep.2 > > setitimer(2) accepts intervals up to UINT_MAX seconds. This is not > documented yet, but I have a rewrite for getitimer.2 in the works. > The kernel enforces it in itimerfix(): I see. OK millert@ - todd
Re: iostat(8): implement periodic display with setitimer(2)
On Wed, Dec 28, 2022 at 08:23:57AM -0700, Todd C. Miller wrote: > On Wed, 28 Dec 2022 06:51:52 -0600, Scott Cheloha wrote: > > > On Sat, Dec 10, 2022 at 08:09:15AM -0600, Scott Cheloha wrote: > > > As with e.g. kstat(1), implementing a periodic display with > > > nanosleep(2) causes the display interval to drift. Doing it with > > > setitimer(2) prevents drift. > > > > > > ok? > > Looks fine to me. I don't see a reason to change the max interval > though--both values appear arbitrary. Neither are arbitrary. The current maximum of one hundred million seconds is based on the old nanosleep(2) limit prior to the 6.5 release. It was a documented limit; see the manpage from the 6.4 release: http://man.openbsd.org/OpenBSD-6.4/nanosleep.2 setitimer(2) accepts intervals up to UINT_MAX seconds. This is not documented yet, but I have a rewrite for getitimer.2 in the works. The kernel enforces it in itimerfix(): https://github.com/openbsd/src/blob/2b46a8cbba384f799321fc554d4d1c95563ea0a2/sys/kern/kern_time.c#L711
Re: iostat(8): implement periodic display with setitimer(2)
On Wed, 28 Dec 2022 06:51:52 -0600, Scott Cheloha wrote: > On Sat, Dec 10, 2022 at 08:09:15AM -0600, Scott Cheloha wrote: > > As with e.g. kstat(1), implementing a periodic display with > > nanosleep(2) causes the display interval to drift. Doing it with > > setitimer(2) prevents drift. > > > > ok? Looks fine to me. I don't see a reason to change the max interval though--both values appear arbitrary. - todd
Re: iostat(8): implement periodic display with setitimer(2)
On Sat, Dec 10, 2022 at 08:09:15AM -0600, Scott Cheloha wrote:
> As with e.g. kstat(1), implementing a periodic display with
> nanosleep(2) causes the display interval to drift. Doing it with
> setitimer(2) prevents drift.
>
> ok?
Two week ping.
Index: iostat.c
===
RCS file: /cvs/src/usr.sbin/iostat/iostat.c,v
retrieving revision 1.45
diff -u -p -r1.45 iostat.c
--- iostat.c4 Dec 2022 23:50:51 - 1.45
+++ iostat.c28 Dec 2022 12:50:46 -
@@ -68,10 +68,12 @@
#include
#include
+#include
#include
#include
#include
#include
+#include
#include
#include
@@ -85,7 +87,8 @@ extern intdk_ndrive;
kvm_t *kd;
char *nlistf, *memf;
-inthz, reps, interval;
+inthz, reps;
+time_t interval;
static int todo = 0;
volatile sig_atomic_t wantheader;
@@ -100,6 +103,7 @@ volatile sig_atomic_t wantheader;
static void cpustats(void);
static void disk_stats(double);
static void disk_stats2(double);
+static void sigalarm(int);
static void sigheader(int);
static void header(void);
static void usage(void);
@@ -113,9 +117,10 @@ int dkinit(int);
int
main(int argc, char *argv[])
{
+ struct itimerval itv;
const char *errstr;
+ sigset_t empty;
int ch, hdrcnt;
- struct timespec ts;
while ((ch = getopt(argc, argv, "Cc:dDIM:N:Tw:")) != -1)
switch(ch) {
@@ -146,7 +151,7 @@ main(int argc, char *argv[])
todo |= SHOW_TTY;
break;
case 'w':
- interval = strtonum(optarg, 1, 1, );
+ interval = strtonum(optarg, 1, UINT_MAX, );
if (errstr)
errx(1, "wait is %s", errstr);
break;
@@ -169,12 +174,20 @@ main(int argc, char *argv[])
dkreadstats();
selectdrives(argv);
- ts.tv_sec = interval;
- ts.tv_nsec = 0;
-
/* print a new header on sigcont */
signal(SIGCONT, sigheader);
+ if (interval != 0) {
+ if (signal(SIGALRM, sigalarm) == SIG_ERR)
+ err(1, "signal");
+ sigemptyset();
+ itv.it_value.tv_sec = interval;
+ itv.it_value.tv_usec = 0;
+ itv.it_interval = itv.it_value;
+ if (setitimer(ITIMER_REAL, , NULL) == -1)
+ err(1, "setitimer");
+ }
+
for (hdrcnt = 1;;) {
if (!--hdrcnt || wantheader) {
header();
@@ -188,7 +201,7 @@ main(int argc, char *argv[])
if (reps >= 0 && --reps <= 0)
break;
- nanosleep(, NULL);
+ sigsuspend();
dkreadstats();
if (last.dk_ndrive != cur.dk_ndrive)
wantheader = 1;
@@ -196,6 +209,11 @@ main(int argc, char *argv[])
exit(0);
}
+static void
+sigalarm(int signo)
+{
+}
+
/*ARGSUSED*/
static void
sigheader(int signo)
@@ -421,7 +439,7 @@ selectdrives(char *argv[])
errx(1, "invalid interval or drive name: %s", *argv);
}
if (*argv) {
- interval = strtonum(*argv, 1, 1, );
+ interval = strtonum(*argv, 1, UINT_MAX, );
if (errstr)
errx(1, "interval is %s", errstr);
if (*++argv) {
iostat(8): implement periodic display with setitimer(2)
As with e.g. kstat(1), implementing a periodic display with
nanosleep(2) causes the display interval to drift. Doing it with
setitimer(2) prevents drift.
ok?
Index: iostat.c
===
RCS file: /cvs/src/usr.sbin/iostat/iostat.c,v
retrieving revision 1.45
diff -u -p -r1.45 iostat.c
--- iostat.c4 Dec 2022 23:50:51 - 1.45
+++ iostat.c10 Dec 2022 14:00:50 -
@@ -68,10 +68,12 @@
#include
#include
+#include
#include
#include
#include
#include
+#include
#include
#include
@@ -85,7 +87,8 @@ extern intdk_ndrive;
kvm_t *kd;
char *nlistf, *memf;
-inthz, reps, interval;
+inthz, reps;
+time_t interval;
static int todo = 0;
volatile sig_atomic_t wantheader;
@@ -100,6 +103,7 @@ volatile sig_atomic_t wantheader;
static void cpustats(void);
static void disk_stats(double);
static void disk_stats2(double);
+static void sigalarm(int);
static void sigheader(int);
static void header(void);
static void usage(void);
@@ -113,9 +117,10 @@ int dkinit(int);
int
main(int argc, char *argv[])
{
+ struct itimerval itv;
const char *errstr;
+ sigset_t empty;
int ch, hdrcnt;
- struct timespec ts;
while ((ch = getopt(argc, argv, "Cc:dDIM:N:Tw:")) != -1)
switch(ch) {
@@ -146,7 +151,7 @@ main(int argc, char *argv[])
todo |= SHOW_TTY;
break;
case 'w':
- interval = strtonum(optarg, 1, 1, );
+ interval = strtonum(optarg, 1, UINT_MAX, );
if (errstr)
errx(1, "wait is %s", errstr);
break;
@@ -169,12 +174,20 @@ main(int argc, char *argv[])
dkreadstats();
selectdrives(argv);
- ts.tv_sec = interval;
- ts.tv_nsec = 0;
-
/* print a new header on sigcont */
signal(SIGCONT, sigheader);
+ if (interval != 0) {
+ if (signal(SIGALRM, sigalarm) == SIG_ERR)
+ err(1, "signal");
+ sigemptyset();
+ itv.it_value.tv_sec = interval;
+ itv.it_value.tv_usec = 0;
+ itv.it_interval = itv.it_value;
+ if (setitimer(ITIMER_REAL, , NULL) == -1)
+ err(1, "setitimer");
+ }
+
for (hdrcnt = 1;;) {
if (!--hdrcnt || wantheader) {
header();
@@ -188,7 +201,7 @@ main(int argc, char *argv[])
if (reps >= 0 && --reps <= 0)
break;
- nanosleep(, NULL);
+ sigsuspend();
dkreadstats();
if (last.dk_ndrive != cur.dk_ndrive)
wantheader = 1;
@@ -196,6 +209,11 @@ main(int argc, char *argv[])
exit(0);
}
+static void
+sigalarm(int signo)
+{
+}
+
/*ARGSUSED*/
static void
sigheader(int signo)
@@ -421,7 +439,7 @@ selectdrives(char *argv[])
errx(1, "invalid interval or drive name: %s", *argv);
}
if (*argv) {
- interval = strtonum(*argv, 1, 1, );
+ interval = strtonum(*argv, 1, UINT_MAX, );
if (errstr)
errx(1, "interval is %s", errstr);
if (*++argv) {
