From patchwork Tue Jun 28 09:58:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marco Elver X-Patchwork-Id: 12898002 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BAABECCA480 for ; Tue, 28 Jun 2022 09:59:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344587AbiF1J71 (ORCPT ); Tue, 28 Jun 2022 05:59:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344583AbiF1J7O (ORCPT ); Tue, 28 Jun 2022 05:59:14 -0400 Received: from mail-ed1-x549.google.com (mail-ed1-x549.google.com [IPv6:2a00:1450:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F21E92EA1A for ; Tue, 28 Jun 2022 02:59:12 -0700 (PDT) Received: by mail-ed1-x549.google.com with SMTP id c20-20020a05640227d400b004369cf00c6bso9098451ede.22 for ; Tue, 28 Jun 2022 02:59:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=rbZIw4RHxWyjZ7uKCIj1/02nzDfS7BCWoBx2cEn1z+M=; b=oiApGXN2/9s/sFVoceixDAIut228b43B7re12xpbnUERFPtk3h5VrnONGsgEsWqxUz CepjzbassXmVJ76eDCy67Z+EgyN3bvcPONjJ+CWggNnKI1jYdXilj8LMD68RmZUcI4kU 4tqs4HcLOZ/p/oZYzlelGpHvLA7w8PNYpHsGk4RodfygCVdyL2oOVwU9Y4V/XXeqmidi bJp1KeFiUgwqJPXK9L2YbiErnJvtRE5/3evOUmd3hE/AO+u/L87tyGphXzsKbtbQPHOp k5xHN+MGFJMTjXOcyrqvDgFAs5/10AcftdO5la5+DNdTRvbLsWgGFquqjZKQX7ZywfYd cFVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=rbZIw4RHxWyjZ7uKCIj1/02nzDfS7BCWoBx2cEn1z+M=; b=m8tnfTENIrgcdirJhjb8otlau6wD2wFJJaaCZxgQlGXUCAUVQt+SJG60YTLN21Ksyi /jXsfRt/dvwjuL4Gn0qN9elmiNZ9zvK6+GNDgfY63EP1KDC/raOCuApOjBJTOdB4mhvM jvf08qi4wmDDelm0qDMdESinyL6dc+zp9DulmLjsbkXhXINGrk74pi5W7ix6E7c5IWdh NK+B+R0yQpKeWrUKSjQdfX4WYHLhf9pC/CwWkrIVn6vI4eTyCGchjXLqPkc+02LUBql4 bVW25s804cCW19K3eBqUUss9lKq1HvOpE9by8U7gCplyvgtiWux2R4ci236IFJkMCK19 +sog== X-Gm-Message-State: AJIora/EzW/tEcXevkU9h+/nLHLURCtu0Xk0j2GCsTMQdfo+ketccIIJ mj0cVx6JFWFeE1uwJktsNlBAvmgIXQ== X-Google-Smtp-Source: AGRyM1ulAFaW+cabMF408m4D0d8sMqq61HRUg92UKKN1R5zpGh6W/kBxcVHJuMeF6VNW23IvyKP84rAZ2g== X-Received: from elver.muc.corp.google.com ([2a00:79e0:9c:201:3496:744e:315a:b41b]) (user=elver job=sendgmr) by 2002:a05:6402:268a:b0:435:c137:6452 with SMTP id w10-20020a056402268a00b00435c1376452mr22004368edd.419.1656410352317; Tue, 28 Jun 2022 02:59:12 -0700 (PDT) Date: Tue, 28 Jun 2022 11:58:25 +0200 In-Reply-To: <20220628095833.2579903-1-elver@google.com> Message-Id: <20220628095833.2579903-6-elver@google.com> Mime-Version: 1.0 References: <20220628095833.2579903-1-elver@google.com> X-Mailer: git-send-email 2.37.0.rc0.161.g10f37bed90-goog Subject: [PATCH v2 05/13] perf/hw_breakpoint: Optimize constant number of breakpoint slots From: Marco Elver To: elver@google.com, Peter Zijlstra , Frederic Weisbecker , Ingo Molnar Cc: Thomas Gleixner , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Dmitry Vyukov , Michael Ellerman , 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 Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Optimize internal hw_breakpoint state if the architecture's number of breakpoint slots is constant. This avoids several kmalloc() calls and potentially unnecessary failures if the allocations fail, as well as subtly improves code generation and cache locality. The protocol is that if an architecture defines hw_breakpoint_slots via the preprocessor, it must be constant and the same for all types. Signed-off-by: Marco Elver Acked-by: Dmitry Vyukov --- arch/sh/include/asm/hw_breakpoint.h | 5 +- arch/x86/include/asm/hw_breakpoint.h | 5 +- kernel/events/hw_breakpoint.c | 92 ++++++++++++++++++---------- 3 files changed, 62 insertions(+), 40 deletions(-) diff --git a/arch/sh/include/asm/hw_breakpoint.h b/arch/sh/include/asm/hw_breakpoint.h index 199d17b765f2..361a0f57bdeb 100644 --- a/arch/sh/include/asm/hw_breakpoint.h +++ b/arch/sh/include/asm/hw_breakpoint.h @@ -48,10 +48,7 @@ struct pmu; /* Maximum number of UBC channels */ #define HBP_NUM 2 -static inline int hw_breakpoint_slots(int type) -{ - return HBP_NUM; -} +#define hw_breakpoint_slots(type) (HBP_NUM) /* arch/sh/kernel/hw_breakpoint.c */ extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw); diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw_breakpoint.h index a1f0e90d0818..0bc931cd0698 100644 --- a/arch/x86/include/asm/hw_breakpoint.h +++ b/arch/x86/include/asm/hw_breakpoint.h @@ -44,10 +44,7 @@ struct arch_hw_breakpoint { /* Total number of available HW breakpoint registers */ #define HBP_NUM 4 -static inline int hw_breakpoint_slots(int type) -{ - return HBP_NUM; -} +#define hw_breakpoint_slots(type) (HBP_NUM) struct perf_event_attr; struct perf_event; diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index 270be965f829..a089302ddf59 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -40,13 +40,16 @@ struct bp_cpuinfo { /* Number of pinned cpu breakpoints in a cpu */ unsigned int cpu_pinned; /* tsk_pinned[n] is the number of tasks having n+1 breakpoints */ +#ifdef hw_breakpoint_slots + unsigned int tsk_pinned[hw_breakpoint_slots(0)]; +#else unsigned int *tsk_pinned; +#endif /* Number of non-pinned cpu/task breakpoints in a cpu */ unsigned int flexible; /* XXX: placeholder, see fetch_this_slot() */ }; static DEFINE_PER_CPU(struct bp_cpuinfo, bp_cpuinfo[TYPE_MAX]); -static int nr_slots[TYPE_MAX] __ro_after_init; static struct bp_cpuinfo *get_bp_info(int cpu, enum bp_type_idx type) { @@ -73,6 +76,54 @@ struct bp_busy_slots { /* Serialize accesses to the above constraints */ static DEFINE_MUTEX(nr_bp_mutex); +#ifdef hw_breakpoint_slots +/* + * Number of breakpoint slots is constant, and the same for all types. + */ +static_assert(hw_breakpoint_slots(TYPE_INST) == hw_breakpoint_slots(TYPE_DATA)); +static inline int hw_breakpoint_slots_cached(int type) { return hw_breakpoint_slots(type); } +static inline int init_breakpoint_slots(void) { return 0; } +#else +/* + * Dynamic number of breakpoint slots. + */ +static int __nr_bp_slots[TYPE_MAX] __ro_after_init; + +static inline int hw_breakpoint_slots_cached(int type) +{ + return __nr_bp_slots[type]; +} + +static __init int init_breakpoint_slots(void) +{ + int i, cpu, err_cpu; + + for (i = 0; i < TYPE_MAX; i++) + __nr_bp_slots[i] = hw_breakpoint_slots(i); + + for_each_possible_cpu(cpu) { + for (i = 0; i < TYPE_MAX; i++) { + struct bp_cpuinfo *info = get_bp_info(cpu, i); + + info->tsk_pinned = kcalloc(__nr_bp_slots[i], sizeof(int), GFP_KERNEL); + if (!info->tsk_pinned) + goto err; + } + } + + return 0; +err: + for_each_possible_cpu(err_cpu) { + for (i = 0; i < TYPE_MAX; i++) + kfree(get_bp_info(err_cpu, i)->tsk_pinned); + if (err_cpu == cpu) + break; + } + + return -ENOMEM; +} +#endif + __weak int hw_breakpoint_weight(struct perf_event *bp) { return 1; @@ -95,7 +146,7 @@ static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type) unsigned int *tsk_pinned = get_bp_info(cpu, type)->tsk_pinned; int i; - for (i = nr_slots[type] - 1; i >= 0; i--) { + for (i = hw_breakpoint_slots_cached(type) - 1; i >= 0; i--) { if (tsk_pinned[i] > 0) return i + 1; } @@ -312,7 +363,7 @@ static int __reserve_bp_slot(struct perf_event *bp, u64 bp_type) fetch_this_slot(&slots, weight); /* Flexible counters need to keep at least one slot */ - if (slots.pinned + (!!slots.flexible) > nr_slots[type]) + if (slots.pinned + (!!slots.flexible) > hw_breakpoint_slots_cached(type)) return -ENOSPC; ret = arch_reserve_bp_slot(bp); @@ -687,42 +738,19 @@ static struct pmu perf_breakpoint = { int __init init_hw_breakpoint(void) { - int cpu, err_cpu; - int i, ret; - - for (i = 0; i < TYPE_MAX; i++) - nr_slots[i] = hw_breakpoint_slots(i); - - for_each_possible_cpu(cpu) { - for (i = 0; i < TYPE_MAX; i++) { - struct bp_cpuinfo *info = get_bp_info(cpu, i); - - info->tsk_pinned = kcalloc(nr_slots[i], sizeof(int), - GFP_KERNEL); - if (!info->tsk_pinned) { - ret = -ENOMEM; - goto err; - } - } - } + int ret; ret = rhltable_init(&task_bps_ht, &task_bps_ht_params); if (ret) - goto err; + return ret; + + ret = init_breakpoint_slots(); + if (ret) + return ret; constraints_initialized = true; perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT); return register_die_notifier(&hw_breakpoint_exceptions_nb); - -err: - for_each_possible_cpu(err_cpu) { - for (i = 0; i < TYPE_MAX; i++) - kfree(get_bp_info(err_cpu, i)->tsk_pinned); - if (err_cpu == cpu) - break; - } - - return ret; }