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authorAndy Lutomirski <luto@MIT.EDU>2011-05-23 09:31:28 -0400
committerThomas Gleixner <tglx@linutronix.de>2011-05-24 14:51:29 +0200
commit44259b1abfaa8bb819d25d41d71e8e33e25dd36a (patch)
tree6255324c0bf2fef17ec3f7d92cdc88d9bbed44a3 /arch/x86/kernel/tsc.c
parent0f51f2852ccf0fe38a02d340d0ba625e8e32a863 (diff)
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x86-64: Move vread_tsc into a new file with sensible options
vread_tsc is short and hot, and it's userspace code so the usual reasons to enable -pg and turn off sibling calls don't apply. (OK, turning off sibling calls has no effect. But it might someday...) As an added benefit, tsc.c is profilable now. Signed-off-by: Andy Lutomirski <luto@mit.edu> Cc: Andi Kleen <andi@firstfloor.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Borislav Petkov <bp@amd64.org> Link: http://lkml.kernel.org/r/%3C99c6d7f5efa3ccb65b4ac6eb443e1ab7bad47d7b.1306156808.git.luto%40mit.edu%3E Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/tsc.c')
-rw-r--r--arch/x86/kernel/tsc.c34
1 files changed, 0 insertions, 34 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 24249a5..6cc6922 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -763,40 +763,6 @@ static cycle_t read_tsc(struct clocksource *cs)
ret : clocksource_tsc.cycle_last;
}
-#ifdef CONFIG_X86_64
-static cycle_t __vsyscall_fn vread_tsc(void)
-{
- cycle_t ret;
- u64 last;
-
- /*
- * Empirically, a fence (of type that depends on the CPU)
- * before rdtsc is enough to ensure that rdtsc is ordered
- * with respect to loads. The various CPU manuals are unclear
- * as to whether rdtsc can be reordered with later loads,
- * but no one has ever seen it happen.
- */
- rdtsc_barrier();
- ret = (cycle_t)vget_cycles();
-
- last = VVAR(vsyscall_gtod_data).clock.cycle_last;
-
- if (likely(ret >= last))
- return ret;
-
- /*
- * GCC likes to generate cmov here, but this branch is extremely
- * predictable (it's just a funciton of time and the likely is
- * very likely) and there's a data dependence, so force GCC
- * to generate a branch instead. I don't barrier() because
- * we don't actually need a barrier, and if this function
- * ever gets inlined it will generate worse code.
- */
- asm volatile ("");
- return last;
-}
-#endif
-
static void resume_tsc(struct clocksource *cs)
{
clocksource_tsc.cycle_last = 0;
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