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/proc/uptime logic needs to sample timer in case multiple reads are used to read the time

This commit is contained in:
Gregory Nutt 2013-12-14 15:25:23 -06:00
parent 46b77e2544
commit 7a173d58b5
3 changed files with 69 additions and 31 deletions
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2
fs/procfs/fs_procfsproc.c
View File

@ -641,7 +641,7 @@ static int process_dup(FAR const struct file *oldp, FAR struct file *newp)
/* Allocate a new container to hold the task and attribute selection */
newattr = (FAR struct process_file_s *)kzalloc(sizeof(struct process_file_s));
newattr = (FAR struct process_file_s *)kmalloc(sizeof(struct process_file_s));
if (!newattr)
{
fdbg("ERROR: Failed to allocate file attributes\n");

84
fs/procfs/fs_procfsuptime.c
View File

@ -80,6 +80,11 @@
struct uptime_file_s
{
struct procfs_file_s base; /* Base open file structure */
#ifdef CONFIG_SYSTEM_TIME64
uint64_t ticktime; /* Sampled 64-bit timer */
#else
uint32_t ticktime; /* Sampled 32-bit timer */
#endif
char line[UPTIME_LINELEN]; /* Pre-allocated buffer for formatted lines */
};
@ -213,33 +218,23 @@ static ssize_t uptime_read(FAR struct file *filep, FAR char *buffer,
ssize_t ret;
#ifdef CONFIG_SYSTEM_TIME64
/* 32-bit timer */
uint64_t ticktime;
#if !defined(CONFIG_HAVE_DOUBLE) || !defined(CONFIG_LIBC_FLOATINGPOINT)
uint64_t sec;
#endif
uint64_t upticks = clock_systimer64();
#else
uint32_t ticktime;
#if !defined(CONFIG_HAVE_DOUBLE) || !defined(CONFIG_LIBC_FLOATINGPOINT)
uint32_t sec;
#endif
#endif
#if defined(CONFIG_HAVE_DOUBLE) && defined(CONFIG_LIBC_FLOATINGPOINT)
double now = (double)upticks / (double)CLOCKS_PER_SEC;
double now;
#else
uint64_t sec = upticks / CLOCKS_PER_SEC;
unsigned int remainder = (unsigned int)(upticks % CLOCKS_PER_SEC);
unsigned int csec = (100 * remainder + (CLOCKS_PER_SEC / 2)) / CLOCKS_PER_SEC;
#endif
#else
/* 32-bit timer */
uint32_t upticks = clock_systimer();
#if defined(CONFIG_HAVE_DOUBLE) && defined(CONFIG_LIBC_FLOATINGPOINT)
double now = (double)upticks / (double)CLOCKS_PER_SEC;
#else
uint32_t sec = upticks / CLOCKS_PER_SEC;
unsigned int remainder = (unsigned int)(upticks % CLOCKS_PER_SEC);
unsigned int csec = (100 * remainder + (CLOCKS_PER_SEC / 2)) / CLOCKS_PER_SEC;
#endif
unsigned int remainder;
unsigned int csec;
#endif
fvdbg("buffer=%p buflen=%d\n", buffer, (int)buflen);
@ -249,12 +244,41 @@ static ssize_t uptime_read(FAR struct file *filep, FAR char *buffer,
attr = (FAR struct uptime_file_s *)filep->f_priv;
DEBUGASSERT(attr);
#if defined(CONFIG_HAVE_DOUBLE) && defined(CONFIG_LIBC_FLOATINGPOINT)
/* Convert the system up time to seconds + hundredths of seconds */
/* If f_pos is zero, then sample the system time. Otherwise, use
* the cached system time from the previous read(). It is necessary
* save the cached value in case, for example, the user is reading
* the time one byte at a time. In that case, the time must remain
* stable throughout the reads.
*/
linesize = snprintf(attr->line, UPTIME_LINELEN, "%10.2f\n", now);
if (filep->f_pos == 0)
{
#ifdef CONFIG_SYSTEM_TIME64
/* 64-bit timer */
attr->ticktime = clock_systimer64();
#else
/* 32-bit timer */
attr->ticktime = clock_systimer();
#endif
}
ticktime = attr->ticktime;
#if defined(CONFIG_HAVE_DOUBLE) && defined(CONFIG_LIBC_FLOATINGPOINT)
/* Convert the system up time to a seconds + hundredths of seconds string */
now = (double)ticktime / (double)CLOCKS_PER_SEC;
linesize = snprintf(attr->line, UPTIME_LINELEN, "%10.2f\n", now);
#else
/* Convert the system up time to seconds + hundredths of seconds */
sec = ticktime / CLOCKS_PER_SEC;
remainder = (unsigned int)(ticktime % CLOCKS_PER_SEC);
csec = (100 * remainder + (CLOCKS_PER_SEC / 2)) / CLOCKS_PER_SEC;
/* Make sure that rounding did not force the hundredths of a second above 99 */
if (csec > 99)
@ -263,7 +287,7 @@ static ssize_t uptime_read(FAR struct file *filep, FAR char *buffer,
csec -= 100;
}
/* Convert the system up time to seconds + hundredths of seconds */
/* Convert the seconds + hundredths of seconds to a string */
linesize = snprintf(attr->line, UPTIME_LINELEN, "%7lu.%02u\n", sec, csec);
@ -306,16 +330,16 @@ static int uptime_dup(FAR const struct file *oldp, FAR struct file *newp)
/* Allocate a new container to hold the task and attribute selection */
newattr = (FAR struct uptime_file_s *)kzalloc(sizeof(struct uptime_file_s));
newattr = (FAR struct uptime_file_s *)kmalloc(sizeof(struct uptime_file_s));
if (!newattr)
{
fdbg("ERROR: Failed to allocate file attributes\n");
return -ENOMEM;
}
/* The copy the file attribtes from the old attributes to the new */
/* The copy the file attributes from the old attributes to the new */
memcpy(&newattr->base, &oldattr->base, sizeof(struct procfs_file_s));
memcpy(newattr, oldattr, sizeof(struct uptime_file_s));
/* Save the new attributes in the new file structure */

14
sched/Kconfig
View File

@ -39,6 +39,20 @@ config MSEC_PER_TICK
may be defined to inform NuttX that the processor hardware is providing
system timer interrupts at some interrupt interval other than 10 msec.
config SYSTEM_TIME64
bool "64-bit system clock"
default n
---help---
The system timer is incremented at the rate determined by
MSEC_PER_TICK, typically at 100Hz. The count at any given time is
then the "uptime" in units of system timer ticks. By default, the
system time is 32-bits wide. Those defaults provide a range of about
13.6 years which is probably a sufficient range for "uptime".
However, if the system timer rate is significantly higher than 100Hz
and/or if a very long "uptime" is required, then this option can be
selected to support a 64-bit wide timer.
config RR_INTERVAL
int "Round robin timeslice (MSEC)"
default 0