| Message ID | 20240403220328.455786-2-andrii@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [v3,1/2] ftrace: make extra rcu_is_watching() validation check optional | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Wed, 3 Apr 2024 15:03:28 -0700 Andrii Nakryiko <andrii@kernel.org> wrote: > Take into account CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING when validating > that RCU is watching when trying to setup rethooko on a function entry. > > This further (in addition to improvements in the previous patch) > improves BPF multi-kretprobe (which rely on rethook) runtime throughput > by 2.3%, according to BPF benchmarks ([0]). > > [0] https://lore.kernel.org/bpf/CAEf4BzauQ2WKMjZdc9s0rBWa01BYbgwHN6aNDXQSHYia47pQ-w@mail.gmail.com/ > Hi Andrii, Can you make this part depends on !KPROBE_EVENTS_ON_NOTRACE (with this option, kretprobes can be used without ftrace, but with original int3) ? This option should be set N on production system because of safety, just for testing raw kretprobes. Thank you, > Signed-off-by: Andrii Nakryiko <andrii@kernel.org> > --- > kernel/trace/rethook.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c > index fa03094e9e69..15b8aa4048d9 100644 > --- a/kernel/trace/rethook.c > +++ b/kernel/trace/rethook.c > @@ -166,6 +166,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh) > if (unlikely(!handler)) > return NULL; > > +#ifdef CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING > /* > * This expects the caller will set up a rethook on a function entry. > * When the function returns, the rethook will eventually be reclaimed > @@ -174,6 +175,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh) > */ > if (unlikely(!rcu_is_watching())) > return NULL; > +#endif > > return (struct rethook_node *)objpool_pop(&rh->pool); > } > -- > 2.43.0 >
On Tue, Apr 9, 2024 at 3:48 PM Masami Hiramatsu <mhiramat@kernel.org> wrote: > > On Wed, 3 Apr 2024 15:03:28 -0700 > Andrii Nakryiko <andrii@kernel.org> wrote: > > > Take into account CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING when validating > > that RCU is watching when trying to setup rethooko on a function entry. > > > > This further (in addition to improvements in the previous patch) > > improves BPF multi-kretprobe (which rely on rethook) runtime throughput > > by 2.3%, according to BPF benchmarks ([0]). > > > > [0] https://lore.kernel.org/bpf/CAEf4BzauQ2WKMjZdc9s0rBWa01BYbgwHN6aNDXQSHYia47pQ-w@mail.gmail.com/ > > > > Hi Andrii, > > Can you make this part depends on !KPROBE_EVENTS_ON_NOTRACE (with this > option, kretprobes can be used without ftrace, but with original int3) ? Sorry for the late response, I was out on vacation. Makes sense about KPROBE_EVENTS_ON_NOTRACE, I went with this condition: #if defined(CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING) || defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE) Will send an updated revision shortly. > This option should be set N on production system because of safety, > just for testing raw kretprobes. > > Thank you, > > > Signed-off-by: Andrii Nakryiko <andrii@kernel.org> > > --- > > kernel/trace/rethook.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c > > index fa03094e9e69..15b8aa4048d9 100644 > > --- a/kernel/trace/rethook.c > > +++ b/kernel/trace/rethook.c > > @@ -166,6 +166,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh) > > if (unlikely(!handler)) > > return NULL; > > > > +#ifdef CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING > > /* > > * This expects the caller will set up a rethook on a function entry. > > * When the function returns, the rethook will eventually be reclaimed > > @@ -174,6 +175,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh) > > */ > > if (unlikely(!rcu_is_watching())) > > return NULL; > > +#endif > > > > return (struct rethook_node *)objpool_pop(&rh->pool); > > } > > -- > > 2.43.0 > > > > > -- > Masami Hiramatsu (Google) <mhiramat@kernel.org>
diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c index fa03094e9e69..15b8aa4048d9 100644 --- a/kernel/trace/rethook.c +++ b/kernel/trace/rethook.c @@ -166,6 +166,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh) if (unlikely(!handler)) return NULL; +#ifdef CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING /* * This expects the caller will set up a rethook on a function entry. * When the function returns, the rethook will eventually be reclaimed @@ -174,6 +175,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh) */ if (unlikely(!rcu_is_watching())) return NULL; +#endif return (struct rethook_node *)objpool_pop(&rh->pool); }
Take into account CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING when validating that RCU is watching when trying to setup rethooko on a function entry. This further (in addition to improvements in the previous patch) improves BPF multi-kretprobe (which rely on rethook) runtime throughput by 2.3%, according to BPF benchmarks ([0]). [0] https://lore.kernel.org/bpf/CAEf4BzauQ2WKMjZdc9s0rBWa01BYbgwHN6aNDXQSHYia47pQ-w@mail.gmail.com/ Signed-off-by: Andrii Nakryiko <andrii@kernel.org> --- kernel/trace/rethook.c | 2 ++ 1 file changed, 2 insertions(+)