From: Adhemerval Zanella <azanella@linux•vnet.ibm.com>
To: linuxppc-dev@lists•ozlabs.org
Cc: Anton Blanchard <anton@samba•org>
Subject: Re: [PATCH] [RFC] powerpc: Add VDSO version of time
Date: Mon, 22 Apr 2013 16:29:33 -0300 [thread overview]
Message-ID: <51758F9D.4010108@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130419083835.37f1c180@kryten>
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>
---
arch/powerpc/kernel/vdso.c | 4 ++++
arch/powerpc/kernel/vdso32/gettimeofday.S | 26 ++++++++++++++++++++++++++
arch/powerpc/kernel/vdso32/vdso32.lds.S | 1 +
arch/powerpc/kernel/vdso64/gettimeofday.S | 26 ++++++++++++++++++++++++++
arch/powerpc/kernel/vdso64/vdso64.lds.S | 1 +
5 files changed, 58 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 1b2076f..d4f463a 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -113,6 +113,10 @@ static struct vdso_patch_def vdso_patches[] = {
CPU_FTR_USE_TB, 0,
"__kernel_get_tbfreq", NULL
},
+ {
+ CPU_FTR_USE_TB, 0,
+ "__kernel_time", NULL
+ },
};
/*
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index 4ee09ee..27e2f62 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 43200ba..f223409 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: *;
};
diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index e97a9a0..a76b4af 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -164,6 +164,32 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
.cfi_endproc
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 V_LOCAL_FUNC(__get_datapage)
+
+ ld r4,STAMP_XTIME+TSPC64_TV_SEC(r3)
+
+ cmpldi r11,0 /* check if t is NULL */
+ beq 2f
+ std r4,0(r11) /* store result at *t */
+2: mtlr r12
+ crclr cr0*4+so
+ mr r3,r4
+ blr
+ .cfi_endproc
+V_FUNCTION_END(__kernel_time)
+
/*
* This is the core of clock_gettime() and gettimeofday(),
diff --git a/arch/powerpc/kernel/vdso64/vdso64.lds.S b/arch/powerpc/kernel/vdso64/vdso64.lds.S
index e6c1758..e486381 100644
--- a/arch/powerpc/kernel/vdso64/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso64/vdso64.lds.S
@@ -147,6 +147,7 @@ VERSION
__kernel_sync_dicache_p5;
__kernel_sigtramp_rt64;
__kernel_getcpu;
+ __kernel_time;
local: *;
};
prev parent reply other threads:[~2013-04-22 19:30 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-19 19:55 [PATCH] [RFC] powerpc: Add VDSO version of time Adhemerval Zanella
2013-03-20 5:00 ` Benjamin Herrenschmidt
2013-03-21 13:40 ` Adhemerval Zanella
2013-03-26 17:32 ` Adhemerval Zanella
2013-04-04 19:22 ` Adhemerval Zanella
2013-04-05 6:21 ` Michael Ellerman
2013-04-05 18:49 ` Adhemerval Zanella
2013-04-08 14:05 ` Adhemerval Zanella
2013-04-18 5:58 ` Michael Ellerman
2013-04-18 22:38 ` Anton Blanchard
2013-04-22 19:29 ` Adhemerval Zanella [this message]
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