hw-breakpoints: Remove stub unthrottle callback

We support event unthrottling in breakpoint events. It means
that if we have more than sysctl_perf_event_sample_rate/HZ,
perf will throttle, ignoring subsequent events until the next
tick.

So if ptrace exceeds this max rate, it will omit events, which
breaks the ptrace determinism that is supposed to report every
triggered breakpoints. This is likely to happen if we set
sysctl_perf_event_sample_rate to 1.

This patch removes support for unthrottling in breakpoint
events to break throttling and restore ptrace determinism.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: 2.6.33.x <stable@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index bb6006e3e295c1d554c0c442a04413a8ad92acd3..1e8ceadc0d6afcdbc0e45e600ed3fb6544498976 100644 (file)
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -531,8 +531,3 @@ void hw_breakpoint_pmu_read(struct perf_event *bp)
 {
        /* TODO */
 }
-
-void hw_breakpoint_pmu_unthrottle(struct perf_event *bp)
-{
-       /* TODO */
-}

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 967e66143e117096262c65fa646a1570e5f035d3..4d99512ee149762dc913b31a1a58164cdf8d770b 100644 (file)
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -489,5 +489,4 @@ struct pmu perf_ops_bp = {
        .enable         = arch_install_hw_breakpoint,
        .disable        = arch_uninstall_hw_breakpoint,
        .read           = hw_breakpoint_pmu_read,
-       .unthrottle     = hw_breakpoint_pmu_unthrottle
 };