hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

powerpc/pseries: lparcfg calculate PURR on demand 

For SPLPAR, lparcfg provides a sum of PURR registers for all CPUs.
Currently this is done by reading PURR in context switch and timer
interrupt, and storing that into a per-CPU variable. These are summed
to provide the value.

This does not work with all timer schemes (e.g., NO_HZ_FULL), and it
is sub-optimal for performance because it reads the PURR register on
every context switch, although that's been difficult to distinguish
from noise in the contxt_switch microbenchmark.

This patch implements the sum by calling a function on each CPU, to
read and add PURR values of each CPU.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2018-05-05 03:19:30 +10:00 committed by Michael Ellerman
parent 36d632ea83
commit 3d3a6021dd
4 changed files with 10 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/powerpc/include/asm/time.h
View File

@ -196,14 +196,6 @@ extern u64 mulhdu(u64, u64);
extern void div128_by_32(u64 dividend_high, u64 dividend_low,
unsigned divisor, struct div_result *dr);
/* Used to store Processor Utilization register (purr) values */
struct cpu_usage {
u64 current_tb; /* Holds the current purr register values */
};
DECLARE_PER_CPU(struct cpu_usage, cpu_usage_array);
extern void secondary_cpu_time_init(void);
extern void __init time_init(void);

14
arch/powerpc/kernel/process.c
View File

@ -846,10 +846,6 @@ bool ppc_breakpoint_available(void)
}
EXPORT_SYMBOL_GPL(ppc_breakpoint_available);
#ifdef CONFIG_PPC64
DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array);
#endif
static inline bool hw_brk_match(struct arch_hw_breakpoint *a,
struct arch_hw_breakpoint *b)
{
@ -1182,16 +1178,6 @@ struct task_struct *__switch_to(struct task_struct *prev,
WARN_ON(!irqs_disabled());
#ifdef CONFIG_PPC64
/*
* Collect processor utilization data per process
*/
if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
struct cpu_usage *cu = this_cpu_ptr(&cpu_usage_array);
cu->current_tb = mfspr(SPRN_PURR);
}
#endif /* CONFIG_PPC64 */
#ifdef CONFIG_PPC_BOOK3S_64
batch = this_cpu_ptr(&ppc64_tlb_batch);
if (batch->active) {

8
arch/powerpc/kernel/time.c
View File

@ -597,14 +597,6 @@ static void __timer_interrupt(void)
__this_cpu_inc(irq_stat.timer_irqs_others);
}
#ifdef CONFIG_PPC64
/* collect purr register values often, for accurate calculations */
if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
struct cpu_usage *cu = this_cpu_ptr(&cpu_usage_array);
cu->current_tb = mfspr(SPRN_PURR);
}
#endif
trace_timer_interrupt_exit(regs);
}

18
arch/powerpc/platforms/pseries/lparcfg.c
View File

@ -52,18 +52,20 @@
* Track sum of all purrs across all processors. This is used to further
* calculate usage values by different applications
*/
static void cpu_get_purr(void *arg)
{
atomic64_t *sum = arg;
atomic64_add(mfspr(SPRN_PURR), sum);
}
static unsigned long get_purr(void)
{
unsigned long sum_purr = 0;
int cpu;
atomic64_t purr = ATOMIC64_INIT(0);
for_each_possible_cpu(cpu) {
struct cpu_usage *cu;
on_each_cpu(cpu_get_purr, &purr, 1);
cu = &per_cpu(cpu_usage_array, cpu);
sum_purr += cu->current_tb;
}
return sum_purr;
return atomic64_read(&purr);
}
/*