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[PATCH] powerpc: Fix runlatch performance issues

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The runlatch SPR can take a lot of time to write. My original runlatch
code would set it on every exception entry even though most of the time
this was not required. It would also continually set it in the idle
loop, which is an issue on an SMT capable processor.

Now we cache the runlatch value in a threadinfo bit, and only check for
it in decrementer and hardware interrupt exceptions as well as the idle
loop. Boot on POWER3, POWER5 and iseries, and compile tested on pmac32.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Anton Blanchard 2006-02-13 14:48:35 +11:00 committed by Paul Mackerras
parent 47f78a4920
commit cb2c9b2741
5 changed files with 39 additions and 41 deletions
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12
arch/powerpc/kernel/head_64.S
View File

@ -319,7 +319,6 @@ exception_marker:
label##_pSeries: \
HMT_MEDIUM; \
mtspr SPRN_SPRG1,r13; /* save r13 */ \
RUNLATCH_ON(r13); \
EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, label##_common)
#define STD_EXCEPTION_ISERIES(n, label, area) \
@ -327,7 +326,6 @@ label##_pSeries: \
label##_iSeries: \
HMT_MEDIUM; \
mtspr SPRN_SPRG1,r13; /* save r13 */ \
RUNLATCH_ON(r13); \
EXCEPTION_PROLOG_ISERIES_1(area); \
EXCEPTION_PROLOG_ISERIES_2; \
b label##_common
@ -337,7 +335,6 @@ label##_iSeries: \
label##_iSeries: \
HMT_MEDIUM; \
mtspr SPRN_SPRG1,r13; /* save r13 */ \
RUNLATCH_ON(r13); \
EXCEPTION_PROLOG_ISERIES_1(PACA_EXGEN); \
lbz r10,PACAPROCENABLED(r13); \
cmpwi 0,r10,0; \
@ -390,6 +387,7 @@ label##_common: \
label##_common: \
EXCEPTION_PROLOG_COMMON(trap, PACA_EXGEN); \
DISABLE_INTS; \
bl .ppc64_runlatch_on; \
addi r3,r1,STACK_FRAME_OVERHEAD; \
bl hdlr; \
b .ret_from_except_lite
@ -407,7 +405,6 @@ __start_interrupts:
_machine_check_pSeries:
HMT_MEDIUM
mtspr SPRN_SPRG1,r13 /* save r13 */
RUNLATCH_ON(r13)
EXCEPTION_PROLOG_PSERIES(PACA_EXMC, machine_check_common)
. = 0x300
@ -434,7 +431,6 @@ END_FTR_SECTION_IFCLR(CPU_FTR_SLB)
data_access_slb_pSeries:
HMT_MEDIUM
mtspr SPRN_SPRG1,r13
RUNLATCH_ON(r13)
mfspr r13,SPRN_SPRG3 /* get paca address into r13 */
std r3,PACA_EXSLB+EX_R3(r13)
mfspr r3,SPRN_DAR
@ -460,7 +456,6 @@ data_access_slb_pSeries:
instruction_access_slb_pSeries:
HMT_MEDIUM
mtspr SPRN_SPRG1,r13
RUNLATCH_ON(r13)
mfspr r13,SPRN_SPRG3 /* get paca address into r13 */
std r3,PACA_EXSLB+EX_R3(r13)
mfspr r3,SPRN_SRR0 /* SRR0 is faulting address */
@ -491,7 +486,6 @@ instruction_access_slb_pSeries:
.globl system_call_pSeries
system_call_pSeries:
HMT_MEDIUM
RUNLATCH_ON(r9)
mr r9,r13
mfmsr r10
mfspr r13,SPRN_SPRG3
@ -575,7 +569,6 @@ slb_miss_user_pseries:
system_reset_fwnmi:
HMT_MEDIUM
mtspr SPRN_SPRG1,r13 /* save r13 */
RUNLATCH_ON(r13)
EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, system_reset_common)
.globl machine_check_fwnmi
@ -583,7 +576,6 @@ system_reset_fwnmi:
machine_check_fwnmi:
HMT_MEDIUM
mtspr SPRN_SPRG1,r13 /* save r13 */
RUNLATCH_ON(r13)
EXCEPTION_PROLOG_PSERIES(PACA_EXMC, machine_check_common)
#ifdef CONFIG_PPC_ISERIES
@ -894,7 +886,6 @@ unrecov_fer:
.align 7
.globl data_access_common
data_access_common:
RUNLATCH_ON(r10) /* It wont fit in the 0x300 handler */
mfspr r10,SPRN_DAR
std r10,PACA_EXGEN+EX_DAR(r13)
mfspr r10,SPRN_DSISR
@ -1042,6 +1033,7 @@ hardware_interrupt_common:
EXCEPTION_PROLOG_COMMON(0x500, PACA_EXGEN)
hardware_interrupt_entry:
DISABLE_INTS
bl .ppc64_runlatch_on
addi r3,r1,STACK_FRAME_OVERHEAD
bl .do_IRQ
b .ret_from_except_lite

32
arch/powerpc/kernel/process.c
View File

@ -888,3 +888,35 @@ void dump_stack(void)
show_stack(current, NULL);
}
EXPORT_SYMBOL(dump_stack);
#ifdef CONFIG_PPC64
void ppc64_runlatch_on(void)
{
unsigned long ctrl;
if (cpu_has_feature(CPU_FTR_CTRL) && !test_thread_flag(TIF_RUNLATCH)) {
HMT_medium();
ctrl = mfspr(SPRN_CTRLF);
ctrl |= CTRL_RUNLATCH;
mtspr(SPRN_CTRLT, ctrl);
set_thread_flag(TIF_RUNLATCH);
}
}
void ppc64_runlatch_off(void)
{
unsigned long ctrl;
if (cpu_has_feature(CPU_FTR_CTRL) && test_thread_flag(TIF_RUNLATCH)) {
HMT_medium();
clear_thread_flag(TIF_RUNLATCH);
ctrl = mfspr(SPRN_CTRLF);
ctrl &= ~CTRL_RUNLATCH;
mtspr(SPRN_CTRLT, ctrl);
}
}
#endif

1
arch/powerpc/platforms/iseries/setup.c
View File

@ -648,6 +648,7 @@ static void yield_shared_processor(void)
* here and let the timer_interrupt code sort out the actual time.
*/
get_lppaca()->int_dword.fields.decr_int = 1;
ppc64_runlatch_on();
process_iSeries_events();
}

31
include/asm-powerpc/reg.h
View File

@ -615,27 +615,9 @@
#define proc_trap() asm volatile("trap")
#ifdef CONFIG_PPC64
static inline void ppc64_runlatch_on(void)
{
unsigned long ctrl;
if (cpu_has_feature(CPU_FTR_CTRL)) {
ctrl = mfspr(SPRN_CTRLF);
ctrl |= CTRL_RUNLATCH;
mtspr(SPRN_CTRLT, ctrl);
}
}
static inline void ppc64_runlatch_off(void)
{
unsigned long ctrl;
if (cpu_has_feature(CPU_FTR_CTRL)) {
ctrl = mfspr(SPRN_CTRLF);
ctrl &= ~CTRL_RUNLATCH;
mtspr(SPRN_CTRLT, ctrl);
}
}
extern void ppc64_runlatch_on(void);
extern void ppc64_runlatch_off(void);
extern unsigned long scom970_read(unsigned int address);
extern void scom970_write(unsigned int address, unsigned long value);
@ -645,15 +627,6 @@ extern void scom970_write(unsigned int address, unsigned long value);
#define __get_SP() ({unsigned long sp; \
asm volatile("mr %0,1": "=r" (sp)); sp;})
#else /* __ASSEMBLY__ */
#define RUNLATCH_ON(REG) \
BEGIN_FTR_SECTION \
mfspr (REG),SPRN_CTRLF; \
ori (REG),(REG),CTRL_RUNLATCH; \
mtspr SPRN_CTRLT,(REG); \
END_FTR_SECTION_IFSET(CPU_FTR_CTRL)
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_REG_H */

4
include/asm-powerpc/thread_info.h
View File

@ -113,7 +113,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
#define TIF_32BIT 5 /* 32 bit binary */
/* #define SPARE 6 */
#define TIF_RUNLATCH 6 /* Is the runlatch enabled? */
#define TIF_ABI_PENDING 7 /* 32/64 bit switch needed */
#define TIF_SYSCALL_AUDIT 8 /* syscall auditing active */
#define TIF_SINGLESTEP 9 /* singlestepping active */
@ -131,7 +131,7 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_32BIT (1<<TIF_32BIT)
/* #define _SPARE (1<<SPARE) */
#define _TIF_RUNLATCH (1<<TIF_RUNLATCH)
#define _TIF_ABI_PENDING (1<<TIF_ABI_PENDING)
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)