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[PATCH] ppc64: iSeries idle fixups

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- remove min/max yield time, we dont use the values anywhere
- separate shared and dedicated idle loops
- check need_resched again with irqs off to avoid sleeping with pending work
- continually set runlatch off in idle loop, this means we dont need to
  turn the runlatch off on exception exit and suffer that associated
  cost for all exceptions. (A future patch will turn the runlatch on at
  exception entry)

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Anton Blanchard 2005-07-07 17:56:32 -07:00 committed by Linus Torvalds
parent 08d5e3eb4b
commit 3c57bb9f45
1 changed files with 48 additions and 38 deletions
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86
arch/ppc64/kernel/iSeries_setup.c
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@ -834,9 +834,6 @@ static int __init iSeries_src_init(void)
late_initcall(iSeries_src_init);
static unsigned long maxYieldTime = 0;
static unsigned long minYieldTime = 0xffffffffffffffffUL;
static inline void process_iSeries_events(void)
{
asm volatile ("li 0,0x5555; sc" : : : "r0", "r3");
@ -845,7 +842,6 @@ static inline void process_iSeries_events(void)
static void yield_shared_processor(void)
{
unsigned long tb;
unsigned long yieldTime;
HvCall_setEnabledInterrupts(HvCall_MaskIPI |
HvCall_MaskLpEvent |
@ -856,13 +852,6 @@ static void yield_shared_processor(void)
/* Compute future tb value when yield should expire */
HvCall_yieldProcessor(HvCall_YieldTimed, tb+tb_ticks_per_jiffy);
yieldTime = get_tb() - tb;
if (yieldTime > maxYieldTime)
maxYieldTime = yieldTime;
if (yieldTime < minYieldTime)
minYieldTime = yieldTime;
/*
* The decrementer stops during the yield. Force a fake decrementer
* here and let the timer_interrupt code sort out the actual time.
@ -871,45 +860,62 @@ static void yield_shared_processor(void)
process_iSeries_events();
}
static int iSeries_idle(void)
static int iseries_shared_idle(void)
{
struct paca_struct *lpaca;
while (1) {
while (!need_resched() && !hvlpevent_is_pending()) {
local_irq_disable();
ppc64_runlatch_off();
/* Recheck with irqs off */
if (!need_resched() && !hvlpevent_is_pending())
yield_shared_processor();
HMT_medium();
local_irq_enable();
}
ppc64_runlatch_on();
if (hvlpevent_is_pending())
process_iSeries_events();
schedule();
}
return 0;
}
static int iseries_dedicated_idle(void)
{
struct paca_struct *lpaca = get_paca();
long oldval;
/* ensure iSeries run light will be out when idle */
ppc64_runlatch_off();
lpaca = get_paca();
while (1) {
if (lpaca->lppaca.shared_proc) {
if (hvlpevent_is_pending())
process_iSeries_events();
if (!need_resched())
yield_shared_processor();
} else {
oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
if (!oldval) {
set_thread_flag(TIF_POLLING_NRFLAG);
if (!oldval) {
set_thread_flag(TIF_POLLING_NRFLAG);
while (!need_resched()) {
while (!need_resched()) {
ppc64_runlatch_off();
HMT_low();
if (hvlpevent_is_pending()) {
HMT_medium();
if (hvlpevent_is_pending())
process_iSeries_events();
HMT_low();
ppc64_runlatch_on();
process_iSeries_events();
}
HMT_medium();
clear_thread_flag(TIF_POLLING_NRFLAG);
} else {
set_need_resched();
}
HMT_medium();
clear_thread_flag(TIF_POLLING_NRFLAG);
} else {
set_need_resched();
}
ppc64_runlatch_on();
schedule();
ppc64_runlatch_off();
}
return 0;
@ -940,6 +946,10 @@ void __init iSeries_early_setup(void)
ppc_md.get_rtc_time = iSeries_get_rtc_time;
ppc_md.calibrate_decr = iSeries_calibrate_decr;
ppc_md.progress = iSeries_progress;
ppc_md.idle_loop = iSeries_idle;
if (get_paca()->lppaca.shared_proc)
ppc_md.idle_loop = iseries_shared_idle;
else
ppc_md.idle_loop = iseries_dedicated_idle;
}