diff options
| author | Adhemerval Zanella <azanella@linux.vnet.ibm.com> | 2013-04-22 09:29:33 +0000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-04-23 16:05:05 +1000 |
| commit | fcb41a2030abe0eb716ef0798035ef9562097f42 (patch) | |
| tree | 4b063cc1cb872fb9609fd90485c7b602b9fdc57f /arch/powerpc/kernel/vdso32 | |
| parent | af81d7878c641629f2693ae3fdaf74b4af14dfca (diff) | |
| download | linux-fcb41a2030abe0eb716ef0798035ef9562097f42.tar.gz | |
powerpc: Add VDSO version of time
On 04/18/2013 07:38 PM, Anton Blanchard wrote:
> Since you are only reading one long you shouldn't need to check the
> update count and loop, you will always see a consistent value. The
> system call version of time() just does an unprotected load for example.
Fixed.
> With the above change and with Michael's comments covered (decent
> changelog entry and Signed-off-by):
>
> Acked-by: Anton Blanchard <anton@samba.org>
Thanks for the review, below the updated patch:
From: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
This patch implement the time syscall as vDSO. The performance speedups
are:
Baseline PPC32: 380 nsec
Baseline PPC64: 350 nsec
vdso PPC32: 20 nsec
vsdo PPC64: 20 nsec
Tested on 64 bit build with both 32 bit and 64 bit userland.
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/vdso32')
| -rw-r--r-- | arch/powerpc/kernel/vdso32/gettimeofday.S | 26 | ||||
| -rw-r--r-- | arch/powerpc/kernel/vdso32/vdso32.lds.S | 1 |
2 files changed, 27 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S index 4ee09ee2e836..27e2f623210b 100644 --- a/arch/powerpc/kernel/vdso32/gettimeofday.S +++ b/arch/powerpc/kernel/vdso32/gettimeofday.S @@ -181,6 +181,32 @@ V_FUNCTION_END(__kernel_clock_getres) /* + * Exact prototype of time() + * + * time_t time(time *t); + * + */ +V_FUNCTION_BEGIN(__kernel_time) + .cfi_startproc + mflr r12 + .cfi_register lr,r12 + + mr r11,r3 /* r11 holds t */ + bl __get_datapage@local + mr r9, r3 /* datapage ptr in r9 */ + + lwz r3,STAMP_XTIME+TSPEC_TV_SEC(r9) + + cmplwi r11,0 /* check if t is NULL */ + beq 2f + stw r3,0(r11) /* store result at *t */ +2: mtlr r12 + crclr cr0*4+so + blr + .cfi_endproc +V_FUNCTION_END(__kernel_time) + +/* * This is the core of clock_gettime() and gettimeofday(), * it returns the current time in r3 (seconds) and r4. * On entry, r7 gives the resolution of r4, either USEC_PER_SEC diff --git a/arch/powerpc/kernel/vdso32/vdso32.lds.S b/arch/powerpc/kernel/vdso32/vdso32.lds.S index 43200ba2e570..f223409629b9 100644 --- a/arch/powerpc/kernel/vdso32/vdso32.lds.S +++ b/arch/powerpc/kernel/vdso32/vdso32.lds.S @@ -150,6 +150,7 @@ VERSION #ifdef CONFIG_PPC64 __kernel_getcpu; #endif + __kernel_time; local: *; }; |