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| author |   Christophe Leroy <christophe.leroy@c-s.fr> | 2020-04-28 13:16:53 +0000 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2020-06-03 20:50:57 +0200 |
| commit | b91c8c42ffdd5c983923edb38b3c3e112bfe6263 (patch) | |
| tree | e7eeb6e39f0036613e54215cab524b8672070072 /lib/vdso | |
| parent | Merge tag 'x86-timers-2020-06-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (diff) | |
| download | linux-dev-b91c8c42ffdd5c983923edb38b3c3e112bfe6263.tar.xz linux-dev-b91c8c42ffdd5c983923edb38b3c3e112bfe6263.zip | |
lib/vdso: Force inlining of __cvdso_clock_gettime_common()
When adding gettime64() to a 32 bit architecture (namely powerpc/32)
it has been noticed that GCC doesn't inline anymore
__cvdso_clock_gettime_common() because it is called twice
(Once by __cvdso_clock_gettime() and once by
__cvdso_clock_gettime32).
This has the effect of seriously degrading the performance:
Before the implementation of gettime64(), gettime() runs in:
clock-gettime-monotonic-raw: vdso: 1003 nsec/call
clock-gettime-monotonic-coarse: vdso: 592 nsec/call
clock-gettime-monotonic: vdso: 942 nsec/call
When adding a gettime64() entry point, the standard gettime()
performance is degraded by 30% to 50%:
clock-gettime-monotonic-raw: vdso: 1300 nsec/call
clock-gettime-monotonic-coarse: vdso: 900 nsec/call
clock-gettime-monotonic: vdso: 1232 nsec/call
Adding __always_inline() to __cvdso_clock_gettime_common() regains the
original performance.
In terms of code size, the inlining increases the code size by only 176
bytes. This is in the noise for a kernel image.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1ab6a62c356c3bec35d1623563ef9c636205bcda.1588079622.git.christophe.leroy@c-s.fr
Diffstat (limited to 'lib/vdso')
| -rw-r--r-- | lib/vdso/gettimeofday.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c index a2909af4b924..7938d3c4901d 100644 --- a/lib/vdso/gettimeofday.c +++ b/lib/vdso/gettimeofday.c @@ -210,7 +210,7 @@ static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk, return 0; } -static __maybe_unused int +static __always_inline int __cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t clock, struct __kernel_timespec *ts) { |