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[PATCH] i386 apm.c optimization

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- avoid expensive modulo (integer division) which happened
  since APM_MAX_EVENTS is 20 (non-power-of-2)
- kill compiler warnings by initializing two variables
- add __read_mostly to some important static variables that are read often
  (by idle loop etc.)
- constify several structures

Signed-off-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andreas Mohr 2006-06-23 02:04:17 -07:00 committed by Linus Torvalds
parent a0b4da91f4
commit 87af2ffd4c
1 changed files with 22 additions and 17 deletions
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39
arch/i386/kernel/apm.c
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@ -374,14 +374,14 @@ static struct {
unsigned short segment;
} apm_bios_entry;
static int clock_slowed;
static int idle_threshold = DEFAULT_IDLE_THRESHOLD;
static int idle_period = DEFAULT_IDLE_PERIOD;
static int idle_threshold __read_mostly = DEFAULT_IDLE_THRESHOLD;
static int idle_period __read_mostly = DEFAULT_IDLE_PERIOD;
static int set_pm_idle;
static int suspends_pending;
static int standbys_pending;
static int ignore_sys_suspend;
static int ignore_normal_resume;
static int bounce_interval = DEFAULT_BOUNCE_INTERVAL;
static int bounce_interval __read_mostly = DEFAULT_BOUNCE_INTERVAL;
#ifdef CONFIG_APM_RTC_IS_GMT
# define clock_cmos_diff 0
@ -390,8 +390,8 @@ static int bounce_interval = DEFAULT_BOUNCE_INTERVAL;
static long clock_cmos_diff;
static int got_clock_diff;
#endif
static int debug;
static int smp;
static int debug __read_mostly;
static int smp __read_mostly;
static int apm_disabled = -1;
#ifdef CONFIG_SMP
static int power_off;
@ -403,8 +403,8 @@ static int realmode_power_off = 1;
#else
static int realmode_power_off;
#endif
static int exit_kapmd;
static int kapmd_running;
static int exit_kapmd __read_mostly;
static int kapmd_running __read_mostly;
#ifdef CONFIG_APM_ALLOW_INTS
static int allow_ints = 1;
#else
@ -416,15 +416,15 @@ static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
static struct apm_user * user_list;
static DEFINE_SPINLOCK(user_list_lock);
static struct desc_struct bad_bios_desc = { 0, 0x00409200 };
static const struct desc_struct bad_bios_desc = { 0, 0x00409200 };
static char driver_version[] = "1.16ac"; /* no spaces */
static const char driver_version[] = "1.16ac"; /* no spaces */
/*
* APM event names taken from the APM 1.2 specification. These are
* the message codes that the BIOS uses to tell us about events
*/
static char * apm_event_name[] = {
static const char * const apm_event_name[] = {
"system standby",
"system suspend",
"normal resume",
@ -616,7 +616,7 @@ static u8 apm_bios_call(u32 func, u32 ebx_in, u32 ecx_in,
* @ecx_in: ECX register value for BIOS call
* @eax: EAX register on return from the BIOS call
*
* Make a BIOS call that does only returns one value, or just status.
* Make a BIOS call that returns one value only, or just status.
* If there is an error, then the error code is returned in AH
* (bits 8-15 of eax) and this function returns non-zero. This is
* used for simpler BIOS operations. This call may hold interrupts
@ -822,7 +822,7 @@ static void apm_do_busy(void)
#define IDLE_CALC_LIMIT (HZ * 100)
#define IDLE_LEAKY_MAX 16
static void (*original_pm_idle)(void);
static void (*original_pm_idle)(void) __read_mostly;
/**
* apm_cpu_idle - cpu idling for APM capable Linux
@ -1063,7 +1063,8 @@ static int apm_engage_power_management(u_short device, int enable)
static int apm_console_blank(int blank)
{
int error, i;
int error = APM_NOT_ENGAGED; /* silence gcc */
int i;
u_short state;
static const u_short dev[3] = { 0x100, 0x1FF, 0x101 };
@ -1104,7 +1105,8 @@ static int queue_empty(struct apm_user *as)
static apm_event_t get_queued_event(struct apm_user *as)
{
as->event_tail = (as->event_tail + 1) % APM_MAX_EVENTS;
if (++as->event_tail >= APM_MAX_EVENTS)
as->event_tail = 0;
return as->events[as->event_tail];
}
@ -1118,13 +1120,16 @@ static void queue_event(apm_event_t event, struct apm_user *sender)
for (as = user_list; as != NULL; as = as->next) {
if ((as == sender) || (!as->reader))
continue;
as->event_head = (as->event_head + 1) % APM_MAX_EVENTS;
if (++as->event_head >= APM_MAX_EVENTS)
as->event_head = 0;
if (as->event_head == as->event_tail) {
static int notified;
if (notified++ == 0)
printk(KERN_ERR "apm: an event queue overflowed\n");
as->event_tail = (as->event_tail + 1) % APM_MAX_EVENTS;
if (++as->event_tail >= APM_MAX_EVENTS)
as->event_tail = 0;
}
as->events[as->event_head] = event;
if ((!as->suser) || (!as->writer))
@ -1282,7 +1287,7 @@ static void standby(void)
static apm_event_t get_event(void)
{
int error;
apm_event_t event;
apm_event_t event = APM_NO_EVENTS; /* silence gcc */
apm_eventinfo_t info;
static int notified;