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Make the previous behaviour the default, add a sysctl which you

Browse Source 
can set if your hw/sw produces the "calcru negative..." message.

Setting the alternate method (sysctl -w kern.timecounter.method=1)
makes the the get{nano|micro}*() functions call the real thing at
resulting in a measurable but minor overhead.

I decided to NOT have the "calcru" change the method automatically
because you should be aware of this problem if you have it.

The problems currently seen, related to usleep and a few other corners
are fixed for both methods.
This commit is contained in:
Poul-Henning Kamp 1998-11-29 20:31:02 +00:00
parent 5986967ee2
commit 510eb5b9db
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=41415
2 changed files with 84 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
sys/kern/kern_clock.c
View File

@ -37,7 +37,7 @@
* SUCH DAMAGE.
*
* @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
* $Id: kern_clock.c,v 1.84 1998/11/23 09:34:19 sos Exp $
* $Id: kern_clock.c,v 1.85 1998/11/23 09:58:53 phk Exp $
*/
#include <sys/param.h>
@ -101,6 +101,13 @@ long tk_rawcc;
time_t time_second;
/*
* Which update policy to use.
* 0 - every tick, bad hardware may fail with "calcru negative..."
* 1 - more resistent to the above hardware, but less efficient.
*/
static int tco_method;
/*
* Implement a dummy timecounter which we can use until we get a real one
* in the air. This allows the console and other early stuff to use
@ -515,8 +522,12 @@ getmicrotime(struct timeval *tvp)
{
struct timecounter *tc;
tc = timecounter;
*tvp = tc->tc_microtime;
if (!tco_method) {
tc = timecounter;
*tvp = tc->tc_microtime;
} else {
microtime(tvp);
}
}
void
@ -524,8 +535,12 @@ getnanotime(struct timespec *tsp)
{
struct timecounter *tc;
tc = timecounter;
*tsp = tc->tc_nanotime;
if (!tco_method) {
tc = timecounter;
*tsp = tc->tc_nanotime;
} else {
nanotime(tsp);
}
}
void
@ -596,9 +611,13 @@ getmicrouptime(struct timeval *tvp)
{
struct timecounter *tc;
tc = timecounter;
tvp->tv_sec = tc->tc_offset_sec;
tvp->tv_usec = tc->tc_offset_micro;
if (!tco_method) {
tc = timecounter;
tvp->tv_sec = tc->tc_offset_sec;
tvp->tv_usec = tc->tc_offset_micro;
} else {
microuptime(tvp);
}
}
void
@ -606,9 +625,13 @@ getnanouptime(struct timespec *tsp)
{
struct timecounter *tc;
tc = timecounter;
tsp->tv_sec = tc->tc_offset_sec;
tsp->tv_nsec = tc->tc_offset_nano >> 32;
if (!tco_method) {
tc = timecounter;
tsp->tv_sec = tc->tc_offset_sec;
tsp->tv_nsec = tc->tc_offset_nano >> 32;
} else {
nanouptime(tsp);
}
}
void
@ -793,7 +816,7 @@ tco_forward(int force)
force++;
}
if (!force)
if (tco_method && !force)
return;
tc->tc_offset_micro = (tc->tc_offset_nano / 1000) >> 32;
@ -833,6 +856,13 @@ sysctl_kern_timecounter_adjustment SYSCTL_HANDLER_ARGS
SYSCTL_NODE(_kern, OID_AUTO, timecounter, CTLFLAG_RW, 0, "");
SYSCTL_INT(_kern_timecounter, KERN_ARGMAX, method, CTLFLAG_RW, &tco_method, 0,
"This variable determines the method used for updating timecounters. "
"If the default algorithm (0) fails with \"calcru negative...\" messages "
"try the alternate algorithm (1) which handles bad hardware better."
);
SYSCTL_PROC(_kern_timecounter, OID_AUTO, frequency, CTLTYPE_INT | CTLFLAG_RW,
0, sizeof(u_int), sysctl_kern_timecounter_frequency, "I", "");

54
sys/kern/kern_tc.c
View File

@ -37,7 +37,7 @@
* SUCH DAMAGE.
*
* @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
* $Id: kern_clock.c,v 1.84 1998/11/23 09:34:19 sos Exp $
* $Id: kern_clock.c,v 1.85 1998/11/23 09:58:53 phk Exp $
*/
#include <sys/param.h>
@ -101,6 +101,13 @@ long tk_rawcc;
time_t time_second;
/*
* Which update policy to use.
* 0 - every tick, bad hardware may fail with "calcru negative..."
* 1 - more resistent to the above hardware, but less efficient.
*/
static int tco_method;
/*
* Implement a dummy timecounter which we can use until we get a real one
* in the air. This allows the console and other early stuff to use
@ -515,8 +522,12 @@ getmicrotime(struct timeval *tvp)
{
struct timecounter *tc;
tc = timecounter;
*tvp = tc->tc_microtime;
if (!tco_method) {
tc = timecounter;
*tvp = tc->tc_microtime;
} else {
microtime(tvp);
}
}
void
@ -524,8 +535,12 @@ getnanotime(struct timespec *tsp)
{
struct timecounter *tc;
tc = timecounter;
*tsp = tc->tc_nanotime;
if (!tco_method) {
tc = timecounter;
*tsp = tc->tc_nanotime;
} else {
nanotime(tsp);
}
}
void
@ -596,9 +611,13 @@ getmicrouptime(struct timeval *tvp)
{
struct timecounter *tc;
tc = timecounter;
tvp->tv_sec = tc->tc_offset_sec;
tvp->tv_usec = tc->tc_offset_micro;
if (!tco_method) {
tc = timecounter;
tvp->tv_sec = tc->tc_offset_sec;
tvp->tv_usec = tc->tc_offset_micro;
} else {
microuptime(tvp);
}
}
void
@ -606,9 +625,13 @@ getnanouptime(struct timespec *tsp)
{
struct timecounter *tc;
tc = timecounter;
tsp->tv_sec = tc->tc_offset_sec;
tsp->tv_nsec = tc->tc_offset_nano >> 32;
if (!tco_method) {
tc = timecounter;
tsp->tv_sec = tc->tc_offset_sec;
tsp->tv_nsec = tc->tc_offset_nano >> 32;
} else {
nanouptime(tsp);
}
}
void
@ -793,7 +816,7 @@ tco_forward(int force)
force++;
}
if (!force)
if (tco_method && !force)
return;
tc->tc_offset_micro = (tc->tc_offset_nano / 1000) >> 32;
@ -833,6 +856,13 @@ sysctl_kern_timecounter_adjustment SYSCTL_HANDLER_ARGS
SYSCTL_NODE(_kern, OID_AUTO, timecounter, CTLFLAG_RW, 0, "");
SYSCTL_INT(_kern_timecounter, KERN_ARGMAX, method, CTLFLAG_RW, &tco_method, 0,
"This variable determines the method used for updating timecounters. "
"If the default algorithm (0) fails with \"calcru negative...\" messages "
"try the alternate algorithm (1) which handles bad hardware better."
);
SYSCTL_PROC(_kern_timecounter, OID_AUTO, frequency, CTLTYPE_INT | CTLFLAG_RW,
0, sizeof(u_int), sysctl_kern_timecounter_frequency, "I", "");