From: Marco Elver <elver@google.com> To: elver@google.com, Peter Zijlstra <peterz@infradead.org>, Frederic Weisbecker <frederic@kernel.org>, Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de>, Arnaldo Carvalho de Melo <acme@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Alexander Shishkin <alexander.shishkin@linux.intel.com>, Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>, Dmitry Vyukov <dvyukov@google.com>, Michael Ellerman <mpe@ellerman.id.au>, linuxppc-dev@lists.ozlabs.org, linux-perf-users@vger.kernel.org, x86@kernel.org, linux-sh@vger.kernel.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org Subject: [PATCH v2 06/13] perf/hw_breakpoint: Make hw_breakpoint_weight() inlinable Date: Tue, 28 Jun 2022 11:58:26 +0200 [thread overview] Message-ID: <20220628095833.2579903-7-elver@google.com> (raw) In-Reply-To: <20220628095833.2579903-1-elver@google.com> Due to being a __weak function, hw_breakpoint_weight() will cause the compiler to always emit a call to it. This generates unnecessarily bad code (register spills etc.) for no good reason; in fact it appears in profiles of `perf bench -r 100 breakpoint thread -b 4 -p 128 -t 512`: ... 0.70% [kernel] [k] hw_breakpoint_weight ... While a small percentage, no architecture defines its own hw_breakpoint_weight() nor are there users outside hw_breakpoint.c, which makes the fact it is currently __weak a poor choice. Change hw_breakpoint_weight()'s definition to follow a similar protocol to hw_breakpoint_slots(), such that if <asm/hw_breakpoint.h> defines hw_breakpoint_weight(), we'll use it instead. The result is that it is inlined and no longer shows up in profiles. Signed-off-by: Marco Elver <elver@google.com> --- include/linux/hw_breakpoint.h | 1 - kernel/events/hw_breakpoint.c | 4 +++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index 78dd7035d1e5..9fa3547acd87 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -79,7 +79,6 @@ extern int dbg_reserve_bp_slot(struct perf_event *bp); extern int dbg_release_bp_slot(struct perf_event *bp); extern int reserve_bp_slot(struct perf_event *bp); extern void release_bp_slot(struct perf_event *bp); -int hw_breakpoint_weight(struct perf_event *bp); int arch_reserve_bp_slot(struct perf_event *bp); void arch_release_bp_slot(struct perf_event *bp); void arch_unregister_hw_breakpoint(struct perf_event *bp); diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index a089302ddf59..a124786e3ade 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -124,10 +124,12 @@ static __init int init_breakpoint_slots(void) } #endif -__weak int hw_breakpoint_weight(struct perf_event *bp) +#ifndef hw_breakpoint_weight +static inline int hw_breakpoint_weight(struct perf_event *bp) { return 1; } +#endif static inline enum bp_type_idx find_slot_idx(u64 bp_type) { -- 2.37.0.rc0.161.g10f37bed90-goog
WARNING: multiple messages have this Message-ID (diff)
From: Marco Elver <elver@google.com> To: elver@google.com, Peter Zijlstra <peterz@infradead.org>, Frederic Weisbecker <frederic@kernel.org>, Ingo Molnar <mingo@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com>, linux-sh@vger.kernel.org, Alexander Shishkin <alexander.shishkin@linux.intel.com>, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, Arnaldo Carvalho de Melo <acme@kernel.org>, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, kasan-dev@googlegroups.com, Namhyung Kim <namhyung@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Jiri Olsa <jolsa@redhat.com>, Dmitry Vyukov <dvyukov@google.com> Subject: [PATCH v2 06/13] perf/hw_breakpoint: Make hw_breakpoint_weight() inlinable Date: Tue, 28 Jun 2022 11:58:26 +0200 [thread overview] Message-ID: <20220628095833.2579903-7-elver@google.com> (raw) In-Reply-To: <20220628095833.2579903-1-elver@google.com> Due to being a __weak function, hw_breakpoint_weight() will cause the compiler to always emit a call to it. This generates unnecessarily bad code (register spills etc.) for no good reason; in fact it appears in profiles of `perf bench -r 100 breakpoint thread -b 4 -p 128 -t 512`: ... 0.70% [kernel] [k] hw_breakpoint_weight ... While a small percentage, no architecture defines its own hw_breakpoint_weight() nor are there users outside hw_breakpoint.c, which makes the fact it is currently __weak a poor choice. Change hw_breakpoint_weight()'s definition to follow a similar protocol to hw_breakpoint_slots(), such that if <asm/hw_breakpoint.h> defines hw_breakpoint_weight(), we'll use it instead. The result is that it is inlined and no longer shows up in profiles. Signed-off-by: Marco Elver <elver@google.com> --- include/linux/hw_breakpoint.h | 1 - kernel/events/hw_breakpoint.c | 4 +++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index 78dd7035d1e5..9fa3547acd87 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -79,7 +79,6 @@ extern int dbg_reserve_bp_slot(struct perf_event *bp); extern int dbg_release_bp_slot(struct perf_event *bp); extern int reserve_bp_slot(struct perf_event *bp); extern void release_bp_slot(struct perf_event *bp); -int hw_breakpoint_weight(struct perf_event *bp); int arch_reserve_bp_slot(struct perf_event *bp); void arch_release_bp_slot(struct perf_event *bp); void arch_unregister_hw_breakpoint(struct perf_event *bp); diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index a089302ddf59..a124786e3ade 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -124,10 +124,12 @@ static __init int init_breakpoint_slots(void) } #endif -__weak int hw_breakpoint_weight(struct perf_event *bp) +#ifndef hw_breakpoint_weight +static inline int hw_breakpoint_weight(struct perf_event *bp) { return 1; } +#endif static inline enum bp_type_idx find_slot_idx(u64 bp_type) { -- 2.37.0.rc0.161.g10f37bed90-goog
next prev parent reply other threads:[~2022-06-28 9:59 UTC|newest] Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-06-28 9:58 [PATCH v2 00/13] perf/hw_breakpoint: Optimize for thousands of tasks Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 9:58 ` [PATCH v2 01/13] perf/hw_breakpoint: Add KUnit test for constraints accounting Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 12:53 ` Dmitry Vyukov 2022-06-28 12:53 ` Dmitry Vyukov 2022-06-28 13:26 ` Marco Elver 2022-06-28 13:26 ` Marco Elver 2022-06-28 9:58 ` [PATCH v2 02/13] perf/hw_breakpoint: Clean up headers Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 9:58 ` [PATCH v2 03/13] perf/hw_breakpoint: Optimize list of per-task breakpoints Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 13:08 ` Dmitry Vyukov 2022-06-28 13:08 ` Dmitry Vyukov 2022-06-28 14:53 ` Marco Elver 2022-06-28 14:53 ` Marco Elver 2022-06-28 15:27 ` Dmitry Vyukov 2022-06-28 15:27 ` Dmitry Vyukov 2022-06-28 9:58 ` [PATCH v2 04/13] perf/hw_breakpoint: Mark data __ro_after_init Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 9:58 ` [PATCH v2 05/13] perf/hw_breakpoint: Optimize constant number of breakpoint slots Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 9:58 ` Marco Elver [this message] 2022-06-28 9:58 ` [PATCH v2 06/13] perf/hw_breakpoint: Make hw_breakpoint_weight() inlinable Marco Elver 2022-06-28 13:16 ` Dmitry Vyukov 2022-06-28 13:16 ` Dmitry Vyukov 2022-06-28 9:58 ` [PATCH v2 07/13] perf/hw_breakpoint: Remove useless code related to flexible breakpoints Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 13:18 ` Dmitry Vyukov 2022-06-28 13:18 ` Dmitry Vyukov 2022-06-28 9:58 ` [PATCH v2 08/13] powerpc/hw_breakpoint: Avoid relying on caller synchronization Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 13:21 ` Dmitry Vyukov 2022-06-28 13:21 ` Dmitry Vyukov 2022-07-01 8:54 ` Christophe Leroy 2022-07-01 8:54 ` Christophe Leroy 2022-07-01 9:41 ` Marco Elver 2022-07-01 9:41 ` Marco Elver 2022-07-01 10:15 ` Christophe Leroy 2022-07-01 10:15 ` Christophe Leroy 2022-06-28 9:58 ` [PATCH v2 09/13] locking/percpu-rwsem: Add percpu_is_write_locked() and percpu_is_read_locked() Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 14:44 ` Dmitry Vyukov 2022-06-28 14:44 ` Dmitry Vyukov 2022-06-28 9:58 ` [PATCH v2 10/13] perf/hw_breakpoint: Reduce contention with large number of tasks Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 14:45 ` Dmitry Vyukov 2022-06-28 14:45 ` Dmitry Vyukov 2022-06-28 9:58 ` [PATCH v2 11/13] perf/hw_breakpoint: Introduce bp_slots_histogram Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 14:52 ` Dmitry Vyukov 2022-06-28 14:52 ` Dmitry Vyukov 2022-06-28 9:58 ` [PATCH v2 12/13] perf/hw_breakpoint: Optimize max_bp_pinned_slots() for CPU-independent task targets Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 15:41 ` Dmitry Vyukov 2022-06-28 15:41 ` Dmitry Vyukov 2022-06-28 9:58 ` [PATCH v2 13/13] perf/hw_breakpoint: Optimize toggle_bp_slot() " Marco Elver 2022-06-28 9:58 ` Marco Elver 2022-06-28 10:54 ` Marco Elver 2022-06-28 10:54 ` Marco Elver 2022-06-28 15:45 ` Dmitry Vyukov 2022-06-28 15:45 ` Dmitry Vyukov 2022-06-28 16:00 ` Marco Elver 2022-06-28 16:00 ` Marco Elver
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