Messages in this thread Patch in this message | | | From | Christophe Leroy <> | Subject | [RFC PATCH v3 12/12] powerpc/vdso: provide __arch_is_hw_counter_valid() | Date | Mon, 13 Jan 2020 17:08:50 +0000 (UTC) |
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To avoid a double verification of the hw_counter validity, provide __arch_is_hw_counter_valid()
Before: clock-gettime-realtime: vdso: 1078 nsec/call
After: clock-gettime-realtime: vdso: 1064 nsec/call
The * shows the test of the clock type. The > shows the additional test on the counter, that goes away with this patch
Before: 5e0: 81 25 00 04 lwz r9,4(r5) *5e4: 2f 89 00 00 cmpwi cr7,r9,0 *5e8: 40 9e 01 3c bne cr7,724 <__c_kernel_clock_gettime+0x17c> 5ec: 94 21 ff e0 stwu r1,-32(r1) 5f0: 93 61 00 0c stw r27,12(r1) 5f4: 93 81 00 10 stw r28,16(r1) 5f8: 93 a1 00 14 stw r29,20(r1) 5fc: 93 c1 00 18 stw r30,24(r1) 600: 93 e1 00 1c stw r31,28(r1) 604: 7d 8d 42 e6 mftbu r12 608: 7f ac 42 e6 mftb r29 60c: 7c cd 42 e6 mftbu r6 610: 7f 8c 30 40 cmplw cr7,r12,r6 614: 40 9e ff f0 bne cr7,604 <__c_kernel_clock_gettime+0x5c> >618: 2f 8c 00 00 cmpwi cr7,r12,0 61c: 83 6b 00 28 lwz r27,40(r11) 620: 83 8b 00 2c lwz r28,44(r11) 624: 81 45 00 08 lwz r10,8(r5) 628: 80 e5 00 0c lwz r7,12(r5) >62c: 41 9c 00 b4 blt cr7,6e0 <__c_kernel_clock_gettime+0x138> 630: 81 05 00 18 lwz r8,24(r5) 634: 83 c5 00 1c lwz r30,28(r5) 638: 80 cb 00 24 lwz r6,36(r11) 63c: 83 e5 00 00 lwz r31,0(r5) 640: 7f 9f 00 40 cmplw cr7,r31,r0 644: 40 9e 00 84 bne cr7,6c8 <__c_kernel_clock_gettime+0x120>
After: 5e0: 81 25 00 04 lwz r9,4(r5) *5e4: 2f 89 00 00 cmpwi cr7,r9,0 *5e8: 40 9e 01 88 bne cr7,770 <__c_kernel_clock_gettime+0x1c8> 5ec: 94 21 ff e0 stwu r1,-32(r1) 5f0: 93 61 00 0c stw r27,12(r1) 5f4: 93 81 00 10 stw r28,16(r1) 5f8: 93 a1 00 14 stw r29,20(r1) 5fc: 93 c1 00 18 stw r30,24(r1) 600: 93 e1 00 1c stw r31,28(r1) 604: 7f cd 42 e6 mftbu r30 608: 7f ac 42 e6 mftb r29 60c: 7c cd 42 e6 mftbu r6 610: 7f 9e 30 40 cmplw cr7,r30,r6 614: 40 9e ff f0 bne cr7,604 <__c_kernel_clock_gettime+0x5c> 618: 83 6b 00 28 lwz r27,40(r11) 61c: 83 8b 00 2c lwz r28,44(r11) 620: 81 45 00 08 lwz r10,8(r5) 624: 80 e5 00 0c lwz r7,12(r5) 628: 81 05 00 18 lwz r8,24(r5) 62c: 83 e5 00 1c lwz r31,28(r5) 630: 80 cb 00 24 lwz r6,36(r11) 634: 81 85 00 00 lwz r12,0(r5) 638: 7f 8c 00 40 cmplw cr7,r12,r0 63c: 40 9e 00 84 bne cr7,6c0 <__c_kernel_clock_gettime+0x118>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- arch/powerpc/include/asm/vdso/gettimeofday.h | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h index d1e702e0ea86..c5a24f31382e 100644 --- a/arch/powerpc/include/asm/vdso/gettimeofday.h +++ b/arch/powerpc/include/asm/vdso/gettimeofday.h @@ -69,15 +69,18 @@ int clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts) } #endif -static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) +static __always_inline bool __arch_is_hw_counter_valid(s32 clock_mode) { /* * clock_mode == 0 implies that vDSO are enabled otherwise * fallback on syscall. */ - if (clock_mode != 0) - return U64_MAX; + return clock_mode == 0 ? true : false; +} +#define __arch_is_hw_counter_valid __arch_is_hw_counter_valid +static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) +{ return get_tb(); } -- 2.13.3
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