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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 4 Jul 2024 19:03:38 +0200
Subject: [PATCH 4/7] perf: Shrink the size of the recursion counter.
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.10/older/patches-6.10.2-rt14.tar.xz
There are four recursion counter, one for each context. The type of the
counter is `int' but the counter is used as `bool' since it is only
incremented if zero.
The main goal here is to shrink the whole struct into 32bit int which
can later be added task_struct into an existing hole.
Reduce the type of the recursion counter to an unsigned char, keep the
increment/ decrement operation.
Tested-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/20240621091601.18227-1-frederic@kernel.org
Link: https://lore.kernel.org/r/20240704170424.1466941-5-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/events/callchain.c | 2 +-
kernel/events/core.c | 2 +-
kernel/events/internal.h | 4 ++--
3 files changed, 4 insertions(+), 4 deletions(-)
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -29,7 +29,7 @@ static inline size_t perf_callchain_entr
sysctl_perf_event_max_contexts_per_stack));
}
-static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
+static DEFINE_PER_CPU(u8, callchain_recursion[PERF_NR_CONTEXTS]);
static atomic_t nr_callchain_events;
static DEFINE_MUTEX(callchain_mutex);
static struct callchain_cpus_entries *callchain_cpus_entries;
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9776,7 +9776,7 @@ struct swevent_htable {
int hlist_refcount;
/* Recursion avoidance in each contexts */
- int recursion[PERF_NR_CONTEXTS];
+ u8 recursion[PERF_NR_CONTEXTS];
};
static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -208,7 +208,7 @@ arch_perf_out_copy_user(void *dst, const
DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user)
-static inline int get_recursion_context(int *recursion)
+static inline int get_recursion_context(u8 *recursion)
{
unsigned char rctx = interrupt_context_level();
@@ -221,7 +221,7 @@ static inline int get_recursion_context(
return rctx;
}
-static inline void put_recursion_context(int *recursion, int rctx)
+static inline void put_recursion_context(u8 *recursion, int rctx)
{
barrier();
recursion[rctx]--;
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