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Mark 'ticks', 'time_second', and 'time_uptime' as volatile to prevent the

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compiler from caching their values in tight loops.

Reviewed by:	bde
MFC after:	1 week
This commit is contained in:
John Baldwin 2013-01-28 19:38:13 +00:00
parent 4e67575ec9
commit a8df530ddc
6 changed files with 11 additions and 9 deletions
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4
sys/dev/usb/net/if_cdce.c
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@ -500,6 +500,7 @@ cdce_attach(device_t dev)
const struct usb_interface_descriptor *id;
const struct usb_cdc_ethernet_descriptor *ued;
const struct usb_config *pcfg;
uint32_t seed;
int error;
uint8_t i;
uint8_t data_iface_no;
@ -612,8 +613,9 @@ alloc_transfers:
/* fake MAC address */
device_printf(dev, "faking MAC address\n");
seed = ticks;
sc->sc_ue.ue_eaddr[0] = 0x2a;
memcpy(&sc->sc_ue.ue_eaddr[1], &ticks, sizeof(uint32_t));
memcpy(&sc->sc_ue.ue_eaddr[1], &seed, sizeof(uint32_t));
sc->sc_ue.ue_eaddr[5] = device_get_unit(dev);
} else {

4
sys/kern/kern_clock.c
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@ -382,7 +382,7 @@ static void watchdog_config(void *, u_int, int *);
int stathz;
int profhz;
int profprocs;
int ticks;
volatile int ticks;
int psratio;
static DPCPU_DEFINE(int, pcputicks); /* Per-CPU version of ticks. */
@ -469,7 +469,7 @@ void
hardclock(int usermode, uintfptr_t pc)
{
atomic_add_int((volatile int *)&ticks, 1);
atomic_add_int(&ticks, 1);
hardclock_cpu(usermode);
tc_ticktock(1);
cpu_tick_calibration();

4
sys/kern/kern_tc.c
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@ -103,8 +103,8 @@ static struct timecounter *timecounters = &dummy_timecounter;
int tc_min_ticktock_freq = 1;
time_t time_second = 1;
time_t time_uptime = 1;
volatile time_t time_second = 1;
volatile time_t time_uptime = 1;
struct bintime boottimebin;
struct timeval boottime;

2
sys/pci/ncr.c
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@ -1386,7 +1386,7 @@ static char *ncr_name (ncb_p np)
* Kernel variables referenced in the scripts.
* THESE MUST ALL BE ALIGNED TO A 4-BYTE BOUNDARY.
*/
static void *script_kvars[] =
static volatile void *script_kvars[] =
{ &time_second, &ticks, &ncr_cache };
static struct script script0 = {

2
sys/sys/kernel.h
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@ -63,7 +63,7 @@ extern int psratio; /* ratio: prof / stat */
extern int stathz; /* statistics clock's frequency */
extern int profhz; /* profiling clock's frequency */
extern int profprocs; /* number of process's profiling */
extern int ticks;
extern volatile int ticks;
#endif /* _KERNEL */

4
sys/sys/time.h
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@ -287,8 +287,8 @@ struct clockinfo {
void inittodr(time_t base);
void resettodr(void);
extern time_t time_second;
extern time_t time_uptime;
extern volatile time_t time_second;
extern volatile time_t time_uptime;
extern struct bintime boottimebin;
extern struct timeval boottime;