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Commit 57e19bfe authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Linus Torvalds
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[PATCH] s390 update (16/27): timer interrupts. 

Make timer interrupt independent from boot cpu and do several ticks in one
go if a virtual cpu didn't get an interrupt for a period of time > HZ.
parent 9f0ff519
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Showing with 127 additions and 60 deletions
arch/s390/kernel/setup.c
View file @ 57e19bfe
......@@ -52,7 +52,6 @@ unsigned long machine_flags = 0;
struct { unsigned long addr, size, type; } memory_chunk[16] = { { 0 } };
#define CHUNK_READ_WRITE 0
#define CHUNK_READ_ONLY 1
__u16 boot_cpu_addr;
int cpus_initialized = 0;
unsigned long cpu_initialized = 0;
volatile int __cpu_logical_map[NR_CPUS]; /* logical cpu to cpu address */
......@@ -474,8 +473,7 @@ void __init setup_arch(char **cmdline_p)
lowcore->jiffy_timer = -1LL;
set_prefix((__u32) lowcore);
cpu_init();
boot_cpu_addr = S390_lowcore.cpu_data.cpu_addr;
__cpu_logical_map[0] = boot_cpu_addr;
__cpu_logical_map[0] = S390_lowcore.cpu_data.cpu_addr;
/*
* Create kernel page tables and switch to virtual addressing.
......
arch/s390/kernel/smp.c
View file @ 57e19bfe
......@@ -41,7 +41,6 @@
/* prototypes */
extern int cpu_idle(void * unused);
extern __u16 boot_cpu_addr;
extern volatile int __cpu_logical_map[];
/*
......@@ -426,6 +425,7 @@ void smp_ctl_clear_bit(int cr, int bit) {
void __init smp_check_cpus(unsigned int max_cpus)
{
int curr_cpu, num_cpus;
__u16 boot_cpu_addr;
boot_cpu_addr = S390_lowcore.cpu_data.cpu_addr;
current_thread_info()->cpu = 0;
......
arch/s390/kernel/time.c
View file @ 57e19bfe
......@@ -38,11 +38,18 @@
#define USECS_PER_JIFFY ((unsigned long) 1000000/HZ)
#define CLK_TICKS_PER_JIFFY ((unsigned long) USECS_PER_JIFFY << 12)
/*
* Create a small time difference between the timer interrupts
* on the different cpus to avoid lock contention.
*/
#define CPU_DEVIATION (smp_processor_id() << 12)
#define TICK_SIZE tick
u64 jiffies_64;
static ext_int_info_t ext_int_info_timer;
static uint64_t xtime_cc;
static uint64_t init_timer_cc;
extern rwlock_t xtime_lock;
......@@ -118,38 +125,68 @@ void do_settimeofday(struct timeval *tv)
write_unlock_irq(&xtime_lock);
}
static inline __u32 div64_32(__u64 dividend, __u32 divisor)
{
register_pair rp;
rp.pair = dividend;
asm ("dr %0,%1" : "+d" (rp) : "d" (divisor));
return rp.subreg.odd;
}
/*
* timer_interrupt() needs to keep up the real-time clock,
* as well as call the "do_timer()" routine every clocktick
*/
#ifdef CONFIG_SMP
extern __u16 boot_cpu_addr;
#endif
static void do_comparator_interrupt(struct pt_regs *regs, __u16 error_code)
{
int cpu = smp_processor_id();
__u64 tmp;
__u32 ticks;
/* Calculate how many ticks have passed. */
asm volatile ("STCK 0(%0)" : : "a" (&tmp) : "memory", "cc");
tmp = tmp - S390_lowcore.jiffy_timer;
if (tmp >= 2*CLK_TICKS_PER_JIFFY) { /* more than one tick ? */
ticks = div64_32(tmp >> 1, CLK_TICKS_PER_JIFFY >> 1);
S390_lowcore.jiffy_timer +=
CLK_TICKS_PER_JIFFY * (__u64) ticks;
} else {
ticks = 1;
S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY;
}
/* set clock comparator for next tick */
tmp = S390_lowcore.jiffy_timer + CLK_TICKS_PER_JIFFY + CPU_DEVIATION;
asm volatile ("SCKC %0" : : "m" (tmp));
irq_enter();
#ifdef CONFIG_SMP
/*
* set clock comparator for next tick
* Do not rely on the boot cpu to do the calls to do_timer.
* Spread it over all cpus instead.
*/
S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY;
asm volatile ("SCKC %0" : : "m" (S390_lowcore.jiffy_timer));
#ifdef CONFIG_SMP
if (S390_lowcore.cpu_data.cpu_addr == boot_cpu_addr)
write_lock(&xtime_lock);
update_process_times(user_mode(regs));
if (S390_lowcore.cpu_data.cpu_addr == boot_cpu_addr) {
if (S390_lowcore.jiffy_timer > xtime_cc) {
__u32 xticks;
tmp = S390_lowcore.jiffy_timer - xtime_cc;
if (tmp >= 2*CLK_TICKS_PER_JIFFY) {
xticks = div64_32(tmp >> 1, CLK_TICKS_PER_JIFFY >> 1);
xtime_cc += (__u64) xticks * CLK_TICKS_PER_JIFFY;
} else {
xticks = 1;
xtime_cc += CLK_TICKS_PER_JIFFY;
}
while (xticks--)
do_timer(regs);
write_unlock(&xtime_lock);
}
write_unlock(&xtime_lock);
while (ticks--)
update_process_times(user_mode(regs));
#else
while (ticks--)
do_timer(regs);
#endif
......@@ -157,19 +194,21 @@ static void do_comparator_interrupt(struct pt_regs *regs, __u16 error_code)
}
/*
* Start the clock comparator on the current CPU
* Start the clock comparator on the current CPU.
*/
void init_cpu_timer(void)
{
unsigned long cr0;
__u64 timer;
/* allow clock comparator timer interrupt */
asm volatile ("STCTL 0,0,%0" : "=m" (cr0) : : "memory");
cr0 |= 0x800;
asm volatile ("LCTL 0,0,%0" : : "m" (cr0) : "memory");
S390_lowcore.jiffy_timer = (__u64) jiffies * CLK_TICKS_PER_JIFFY;
S390_lowcore.jiffy_timer += init_timer_cc + CLK_TICKS_PER_JIFFY;
asm volatile ("SCKC %0" : : "m" (S390_lowcore.jiffy_timer));
timer = init_timer_cc + jiffies_64 * CLK_TICKS_PER_JIFFY;
S390_lowcore.jiffy_timer = timer;
timer += CLK_TICKS_PER_JIFFY + CPU_DEVIATION;
asm volatile ("SCKC %0" : : "m" (timer));
}
/*
......@@ -201,6 +240,7 @@ void __init time_init(void)
}
/* set xtime */
xtime_cc = init_timer_cc;
set_time_cc = init_timer_cc - 0x8126d60e46000000LL +
(0x3c26700LL*1000000*4096);
tod_to_timeval(set_time_cc, &xtime);
......
arch/s390x/kernel/setup.c
View file @ 57e19bfe
......@@ -52,7 +52,6 @@ unsigned long machine_flags = 0;
struct { unsigned long addr, size, type; } memory_chunk[16] = { { 0 } };
#define CHUNK_READ_WRITE 0
#define CHUNK_READ_ONLY 1
__u16 boot_cpu_addr;
int cpus_initialized = 0;
unsigned long cpu_initialized = 0;
volatile int __cpu_logical_map[NR_CPUS]; /* logical cpu to cpu address */
......@@ -464,8 +463,7 @@ void __init setup_arch(char **cmdline_p)
lowcore->jiffy_timer = -1LL;
set_prefix((__u32)(__u64) lowcore);
cpu_init();
boot_cpu_addr = S390_lowcore.cpu_data.cpu_addr;
__cpu_logical_map[0] = boot_cpu_addr;
__cpu_logical_map[0] = S390_lowcore.cpu_data.cpu_addr;
/*
* Create kernel page tables and switch to virtual addressing.
......
arch/s390x/kernel/smp.c
View file @ 57e19bfe
......@@ -40,7 +40,6 @@
/* prototypes */
extern int cpu_idle(void * unused);
extern __u16 boot_cpu_addr;
extern volatile int __cpu_logical_map[];
/*
......@@ -407,6 +406,7 @@ void smp_ctl_clear_bit(int cr, int bit) {
void __init smp_check_cpus(unsigned int max_cpus)
{
int curr_cpu, num_cpus;
__u16 boot_cpu_addr;
boot_cpu_addr = S390_lowcore.cpu_data.cpu_addr;
current_thread_info()->cpu = 0;
......
arch/s390x/kernel/time.c
View file @ 57e19bfe
......@@ -37,11 +37,18 @@
#define USECS_PER_JIFFY ((unsigned long) 1000000/HZ)
#define CLK_TICKS_PER_JIFFY ((unsigned long) USECS_PER_JIFFY << 12)
/*
* Create a small time difference between the timer interrupts
* on the different cpus to avoid lock contention.
*/
#define CPU_DEVIATION (smp_processor_id() << 12)
#define TICK_SIZE tick
u64 jiffies_64;
static ext_int_info_t ext_int_info_timer;
static uint64_t xtime_cc;
static uint64_t init_timer_cc;
extern rwlock_t xtime_lock;
......@@ -117,34 +124,55 @@ void do_settimeofday(struct timeval *tv)
* timer_interrupt() needs to keep up the real-time clock,
* as well as call the "do_timer()" routine every clocktick
*/
#ifdef CONFIG_SMP
extern __u16 boot_cpu_addr;
#endif
static void do_comparator_interrupt(struct pt_regs *regs, __u16 error_code)
{
int cpu = smp_processor_id();
__u64 tmp;
__u32 ticks;
/* Calculate how many ticks have passed. */
asm volatile ("STCK 0(%0)" : : "a" (&tmp) : "memory", "cc");
tmp = tmp - S390_lowcore.jiffy_timer;
if (tmp >= 2*CLK_TICKS_PER_JIFFY) { /* more than one tick ? */
ticks = tmp / CLK_TICKS_PER_JIFFY;
S390_lowcore.jiffy_timer +=
CLK_TICKS_PER_JIFFY * (__u64) ticks;
} else {
ticks = 1;
S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY;
}
/* set clock comparator for next tick */
tmp = S390_lowcore.jiffy_timer + CLK_TICKS_PER_JIFFY + CPU_DEVIATION;
asm volatile ("SCKC %0" : : "m" (tmp));
irq_enter();
#ifdef CONFIG_SMP
/*
* set clock comparator for next tick
* Do not rely on the boot cpu to do the calls to do_timer.
* Spread it over all cpus instead.
*/
S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY;
asm volatile ("SCKC %0" : : "m" (S390_lowcore.jiffy_timer));
#ifdef CONFIG_SMP
if (S390_lowcore.cpu_data.cpu_addr == boot_cpu_addr)
write_lock(&xtime_lock);
update_process_times(user_mode(regs));
if (S390_lowcore.cpu_data.cpu_addr == boot_cpu_addr) {
if (S390_lowcore.jiffy_timer > xtime_cc) {
__u32 xticks;
tmp = S390_lowcore.jiffy_timer - xtime_cc;
if (tmp >= 2*CLK_TICKS_PER_JIFFY) {
xticks = tmp / CLK_TICKS_PER_JIFFY;
xtime_cc += (__u64) xticks * CLK_TICKS_PER_JIFFY;
} else {
xticks = 1;
xtime_cc += CLK_TICKS_PER_JIFFY;
}
while (xticks--)
do_timer(regs);
write_unlock(&xtime_lock);
}
write_unlock(&xtime_lock);
while (ticks--)
update_process_times(user_mode(regs));
#else
while (ticks--)
do_timer(regs);
#endif
......@@ -152,19 +180,21 @@ static void do_comparator_interrupt(struct pt_regs *regs, __u16 error_code)
}
/*
* Start the clock comparator on the current CPU
* Start the clock comparator on the current CPU.
*/
void init_cpu_timer(void)
{
unsigned long cr0;
__u64 timer;
/* allow clock comparator timer interrupt */
asm volatile ("STCTG 0,0,%0" : "=m" (cr0) : : "memory");
cr0 |= 0x800;
asm volatile ("LCTLG 0,0,%0" : : "m" (cr0) : "memory");
S390_lowcore.jiffy_timer = (__u64) jiffies * CLK_TICKS_PER_JIFFY;
S390_lowcore.jiffy_timer += init_timer_cc + CLK_TICKS_PER_JIFFY;
asm volatile ("SCKC %0" : : "m" (S390_lowcore.jiffy_timer));
timer = init_timer_cc + jiffies_64 * CLK_TICKS_PER_JIFFY;
S390_lowcore.jiffy_timer = timer;
timer += CLK_TICKS_PER_JIFFY + CPU_DEVIATION;
asm volatile ("SCKC %0" : : "m" (timer));
}
/*
......@@ -196,6 +226,7 @@ void __init time_init(void)
}
/* set xtime */
xtime_cc = init_timer_cc;
set_time_cc = init_timer_cc - 0x8126d60e46000000LL +
(0x3c26700LL*1000000*4096);
tod_to_timeval(set_time_cc, &xtime);
......
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