Commit c76101e8 authored by Anton Blanchard's avatar Anton Blanchard Committed by Linus Torvalds

[PATCH] ppc64: clean up idle loop code

Clean up our idle loop code:

- Remove a bunch of useless includes and make most functions static
- There were places where we werent disabling interrupts before checking
  need_resched then calling the hypervisor to sleep our thread. We might
  race with an IPI and end up missing a reschedule. Disable interrupts
  around these regions to make them safe.
- We forgot to turn off the polling flag when exiting the dedicated_idle
  idle loop. This could have resulted in all manner problems as other
  cpus would avoid sending IPIs to force reschedules.
- Add a missing check for cpu_is_offline in the shared cpu idle loop.
Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f4b0a775
......@@ -16,28 +16,16 @@
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/cpu.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/cache.h>
#include <asm/cputable.h>
#include <asm/time.h>
#include <asm/iSeries/LparData.h>
#include <asm/iSeries/HvCall.h>
#include <asm/iSeries/ItLpQueue.h>
......@@ -45,11 +33,11 @@ extern long cede_processor(void);
extern long poll_pending(void);
extern void power4_idle(void);
int (*idle_loop)(void);
static int (*idle_loop)(void);
#ifdef CONFIG_PPC_ISERIES
unsigned long maxYieldTime = 0;
unsigned long minYieldTime = 0xffffffffffffffffUL;
static unsigned long maxYieldTime = 0;
static unsigned long minYieldTime = 0xffffffffffffffffUL;
static void yield_shared_processor(void)
{
......@@ -80,7 +68,7 @@ static void yield_shared_processor(void)
process_iSeries_events();
}
int iSeries_idle(void)
static int iSeries_idle(void)
{
struct paca_struct *lpaca;
long oldval;
......@@ -91,13 +79,10 @@ int iSeries_idle(void)
CTRL = mfspr(CTRLF);
CTRL &= ~RUNLATCH;
mtspr(CTRLT, CTRL);
#if 0
init_idle();
#endif
lpaca = get_paca();
for (;;) {
while (1) {
if (lpaca->lppaca.xSharedProc) {
if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
process_iSeries_events();
......@@ -125,11 +110,13 @@ int iSeries_idle(void)
schedule();
}
return 0;
}
#endif
int default_idle(void)
#else
static int default_idle(void)
{
long oldval;
unsigned int cpu = smp_processor_id();
......@@ -164,8 +151,6 @@ int default_idle(void)
return 0;
}
#ifdef CONFIG_PPC_PSERIES
DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
int dedicated_idle(void)
......@@ -179,8 +164,10 @@ int dedicated_idle(void)
ppaca = &paca[cpu ^ 1];
while (1) {
/* Indicate to the HV that we are idle. Now would be
* a good time to find other work to dispatch. */
/*
* Indicate to the HV that we are idle. Now would be
* a good time to find other work to dispatch.
*/
lpaca->lppaca.xIdle = 1;
oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
......@@ -203,21 +190,17 @@ int dedicated_idle(void)
HMT_medium();
if (!(ppaca->lppaca.xIdle)) {
/* Indicate we are no longer polling for
* work, and then clear need_resched. If
* need_resched was 1, set it back to 1
* and schedule work
local_irq_disable();
/*
* We are about to sleep the thread
* and so wont be polling any
* more.
*/
clear_thread_flag(TIF_POLLING_NRFLAG);
oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
if(oldval == 1) {
set_need_resched();
break;
}
local_irq_disable();
/* SMT dynamic mode. Cede will result
/*
* SMT dynamic mode. Cede will result
* in this thread going dormant, if the
* partner thread is still doing work.
* Thread wakes up if partner goes idle,
......@@ -225,15 +208,21 @@ int dedicated_idle(void)
* occurs. Returning from the cede
* enables external interrupts.
*/
if (!need_resched())
cede_processor();
else
local_irq_enable();
} else {
/* Give the HV an opportunity at the
/*
* Give the HV an opportunity at the
* processor, since we are not doing
* any work.
*/
poll_pending();
}
}
clear_thread_flag(TIF_POLLING_NRFLAG);
} else {
set_need_resched();
}
......@@ -247,20 +236,19 @@ int dedicated_idle(void)
return 0;
}
int shared_idle(void)
static int shared_idle(void)
{
struct paca_struct *lpaca = get_paca();
unsigned int cpu = smp_processor_id();
while (1) {
if (cpu_is_offline(smp_processor_id()) &&
system_state == SYSTEM_RUNNING)
cpu_die();
/* Indicate to the HV that we are idle. Now would be
* a good time to find other work to dispatch. */
/*
* Indicate to the HV that we are idle. Now would be
* a good time to find other work to dispatch.
*/
lpaca->lppaca.xIdle = 1;
if (!need_resched()) {
while (!need_resched() && !cpu_is_offline(cpu)) {
local_irq_disable();
/*
......@@ -269,26 +257,28 @@ int shared_idle(void)
* to returning here) or if a prod occurs from another
* processor. When returning here, external interrupts
* are enabled.
*
* Check need_resched() again with interrupts disabled
* to avoid a race.
*/
if (!need_resched())
cede_processor();
else
local_irq_enable();
}
HMT_medium();
lpaca->lppaca.xIdle = 0;
schedule();
if (cpu_is_offline(smp_processor_id()) &&
system_state == SYSTEM_RUNNING)
cpu_die();
}
return 0;
}
#endif
int cpu_idle(void)
{
idle_loop();
return 0;
}
int native_idle(void)
static int powermac_idle(void)
{
while(1) {
if (!need_resched())
......@@ -298,6 +288,13 @@ int native_idle(void)
}
return 0;
}
#endif
int cpu_idle(void)
{
idle_loop();
return 0;
}
int idle_setup(void)
{
......@@ -318,8 +315,8 @@ int idle_setup(void)
idle_loop = default_idle;
}
} else if (systemcfg->platform == PLATFORM_POWERMAC) {
printk("idle = native_idle\n");
idle_loop = native_idle;
printk("idle = powermac_idle\n");
idle_loop = powermac_idle;
} else {
printk("idle_setup: unknown platform, use default_idle\n");
idle_loop = default_idle;
......@@ -328,4 +325,3 @@ int idle_setup(void)
return 1;
}
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