From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 626D2C43331 for ; Tue, 24 Mar 2020 14:25:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2889120788 for ; Tue, 24 Mar 2020 14:25:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="19Uf+Au/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728706AbgCXOZT (ORCPT ); Tue, 24 Mar 2020 10:25:19 -0400 Received: from merlin.infradead.org ([205.233.59.134]:53678 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728484AbgCXOYy (ORCPT ); Tue, 24 Mar 2020 10:24:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=i/KkA+KRxg5HQAbK1lOGn88zYvb4swUMzi9VljGrPKY=; b=19Uf+Au/aN0hm+QNLBx7Cps5ei ICjaoftp4gLH6AQMwir65fcZQF7yCS7xK1sIpG9CtZCX1tToESA1TwS7Mpv8k/bCZe01QdE/5qW5r jPTubdFNEj2wp+P1PatAnvRqZLIPio4y7DuvaDv+8HzoSZTs1xN5qesU5TcN6KI1rK7dn1lgJSAel qhmh/M+vbt1JoGWrN58mCQoFK3BkXz2wgk0nCMMDMqCJS5JsLkUFxgRdfqljOCRIWc0iDzjC9euoD QFo6D58yECZ3cFuaUtxi1O3Ys7VQo2XAZMHIfhqMNgNq67Y3ewcazRLwXwL6Gvd+24IIwGAqU7o6P TBv9UkFQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jGkTv-0003oo-7v; Tue, 24 Mar 2020 14:24:39 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 82051307967; Tue, 24 Mar 2020 15:24:35 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 223A5286C13B9; Tue, 24 Mar 2020 15:24:35 +0100 (CET) Message-Id: <20200324142246.005164711@infradead.org> User-Agent: quilt/0.65 Date: Tue, 24 Mar 2020 14:56:15 +0100 From: Peter Zijlstra To: x86@kernel.org Cc: peterz@infradead.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, bristot@redhat.com, jbaron@akamai.com, torvalds@linux-foundation.org, tglx@linutronix.de, mingo@kernel.org, namit@vmware.com, hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org, jpoimboe@redhat.com Subject: [RESEND][PATCH v3 12/17] tracepoint: Optimize using static_call() References: <20200324135603.483964896@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" Currently the tracepoint site will iterate a vector and issue indirect calls to however many handlers are registered (ie. the vector is long). Using static_call() it is possible to optimize this for the common case of only having a single handler registered. In this case the static_call() can directly call this handler. Otherwise, if the vector is longer than 1, call a function that iterates the whole vector like the current code. [peterz: updated to new interface] Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Peter Zijlstra (Intel) --- include/linux/tracepoint-defs.h | 5 ++ include/linux/tracepoint.h | 78 +++++++++++++++++++++++++++------------- include/trace/define_trace.h | 14 +++---- kernel/tracepoint.c | 21 ++++++++-- 4 files changed, 82 insertions(+), 36 deletions(-) --- a/include/linux/tracepoint-defs.h +++ b/include/linux/tracepoint-defs.h @@ -11,6 +11,8 @@ #include #include +struct static_call_key; + struct trace_print_flags { unsigned long mask; const char *name; @@ -30,6 +32,9 @@ struct tracepoint_func { struct tracepoint { const char *name; /* Tracepoint name */ struct static_key key; + struct static_call_key *static_call_key; + void *static_call_tramp; + void *iterator; int (*regfunc)(void); void (*unregfunc)(void); struct tracepoint_func __rcu *funcs; --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -19,6 +19,7 @@ #include #include #include +#include struct module; struct tracepoint; @@ -92,7 +93,9 @@ extern int syscall_regfunc(void); extern void syscall_unregfunc(void); #endif /* CONFIG_HAVE_SYSCALL_TRACEPOINTS */ +#ifndef PARAMS #define PARAMS(args...) args +#endif #define TRACE_DEFINE_ENUM(x) #define TRACE_DEFINE_SIZEOF(x) @@ -159,12 +162,11 @@ static inline struct tracepoint *tracepo * as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just * "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto". */ -#define __DO_TRACE(tp, proto, args, cond, rcuidle) \ +#define __DO_TRACE(name, proto, args, cond, rcuidle) \ do { \ struct tracepoint_func *it_func_ptr; \ - void *it_func; \ - void *__data; \ int __maybe_unused __idx = 0; \ + void *__data; \ \ if (!(cond)) \ return; \ @@ -184,14 +186,11 @@ static inline struct tracepoint *tracepo rcu_irq_enter_irqson(); \ } \ \ - it_func_ptr = rcu_dereference_raw((tp)->funcs); \ - \ + it_func_ptr = \ + rcu_dereference_raw((&__tracepoint_##name)->funcs); \ if (it_func_ptr) { \ - do { \ - it_func = (it_func_ptr)->func; \ - __data = (it_func_ptr)->data; \ - ((void(*)(proto))(it_func))(args); \ - } while ((++it_func_ptr)->func); \ + __data = (it_func_ptr)->data; \ + static_call(tp_func_##name)(args); \ } \ \ if (rcuidle) { \ @@ -207,7 +206,7 @@ static inline struct tracepoint *tracepo static inline void trace_##name##_rcuidle(proto) \ { \ if (static_key_false(&__tracepoint_##name.key)) \ - __DO_TRACE(&__tracepoint_##name, \ + __DO_TRACE(name, \ TP_PROTO(data_proto), \ TP_ARGS(data_args), \ TP_CONDITION(cond), 1); \ @@ -229,11 +228,13 @@ static inline struct tracepoint *tracepo * poking RCU a bit. */ #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ + extern int __tracepoint_iter_##name(data_proto); \ + DECLARE_STATIC_CALL(tp_func_##name, __tracepoint_iter_##name); \ extern struct tracepoint __tracepoint_##name; \ static inline void trace_##name(proto) \ { \ if (static_key_false(&__tracepoint_##name.key)) \ - __DO_TRACE(&__tracepoint_##name, \ + __DO_TRACE(name, \ TP_PROTO(data_proto), \ TP_ARGS(data_args), \ TP_CONDITION(cond), 0); \ @@ -279,21 +280,48 @@ static inline struct tracepoint *tracepo * structures, so we create an array of pointers that will be used for iteration * on the tracepoints. */ -#define DEFINE_TRACE_FN(name, reg, unreg) \ - static const char __tpstrtab_##name[] \ - __attribute__((section("__tracepoints_strings"))) = #name; \ - struct tracepoint __tracepoint_##name \ - __attribute__((section("__tracepoints"), used)) = \ - { __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\ - __TRACEPOINT_ENTRY(name); +#define DEFINE_TRACE_FN(_name, _reg, _unreg, proto, args) \ + static const char __tpstrtab_##_name[] \ + __attribute__((section("__tracepoints_strings"))) = #_name; \ + extern struct static_call_key tp_func_##_name; \ + int __tracepoint_iter_##_name(void *__data, proto); \ + struct tracepoint __tracepoint_##_name \ + __attribute__((section("__tracepoints"), used)) = { \ + .name = __tpstrtab_##_name, \ + .key = STATIC_KEY_INIT_FALSE, \ + .static_call_key = &STATIC_CALL_NAME(tp_func_##_name), \ + .static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \ + .iterator = &__tracepoint_iter_##_name, \ + .regfunc = _reg, \ + .unregfunc = _unreg, \ + .funcs = NULL }; \ + __TRACEPOINT_ENTRY(_name); \ + int __tracepoint_iter_##_name(void *__data, proto) \ + { \ + struct tracepoint_func *it_func_ptr; \ + void *it_func; \ + \ + it_func_ptr = \ + rcu_dereference_raw((&__tracepoint_##_name)->funcs); \ + do { \ + it_func = (it_func_ptr)->func; \ + __data = (it_func_ptr)->data; \ + ((void(*)(void *, proto))(it_func))(__data, args); \ + } while ((++it_func_ptr)->func); \ + return 0; \ + } \ + DEFINE_STATIC_CALL(tp_func_##_name, __tracepoint_iter_##_name); -#define DEFINE_TRACE(name) \ - DEFINE_TRACE_FN(name, NULL, NULL); +#define DEFINE_TRACE(name, proto, args) \ + DEFINE_TRACE_FN(name, NULL, NULL, PARAMS(proto), PARAMS(args)); #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \ - EXPORT_SYMBOL_GPL(__tracepoint_##name) + EXPORT_SYMBOL_GPL(__tracepoint_##name); \ + EXPORT_STATIC_CALL_GPL(tp_func_##name) #define EXPORT_TRACEPOINT_SYMBOL(name) \ - EXPORT_SYMBOL(__tracepoint_##name) + EXPORT_SYMBOL(__tracepoint_##name); \ + EXPORT_STATIC_CALL(tp_func_##name) + #else /* !TRACEPOINTS_ENABLED */ #define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \ @@ -322,8 +350,8 @@ static inline struct tracepoint *tracepo return false; \ } -#define DEFINE_TRACE_FN(name, reg, unreg) -#define DEFINE_TRACE(name) +#define DEFINE_TRACE_FN(name, reg, unreg, proto, args) +#define DEFINE_TRACE(name, proto, args) #define EXPORT_TRACEPOINT_SYMBOL_GPL(name) #define EXPORT_TRACEPOINT_SYMBOL(name) --- a/include/trace/define_trace.h +++ b/include/trace/define_trace.h @@ -25,7 +25,7 @@ #undef TRACE_EVENT #define TRACE_EVENT(name, proto, args, tstruct, assign, print) \ - DEFINE_TRACE(name) + DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) #undef TRACE_EVENT_CONDITION #define TRACE_EVENT_CONDITION(name, proto, args, cond, tstruct, assign, print) \ @@ -39,12 +39,12 @@ #undef TRACE_EVENT_FN #define TRACE_EVENT_FN(name, proto, args, tstruct, \ assign, print, reg, unreg) \ - DEFINE_TRACE_FN(name, reg, unreg) + DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args)) #undef TRACE_EVENT_FN_COND #define TRACE_EVENT_FN_COND(name, proto, args, cond, tstruct, \ assign, print, reg, unreg) \ - DEFINE_TRACE_FN(name, reg, unreg) + DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args)) #undef TRACE_EVENT_NOP #define TRACE_EVENT_NOP(name, proto, args, struct, assign, print) @@ -54,15 +54,15 @@ #undef DEFINE_EVENT #define DEFINE_EVENT(template, name, proto, args) \ - DEFINE_TRACE(name) + DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) #undef DEFINE_EVENT_FN #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg) \ - DEFINE_TRACE_FN(name, reg, unreg) + DEFINE_TRACE_FN(name, reg, unreg, PARAMS(proto), PARAMS(args)) #undef DEFINE_EVENT_PRINT #define DEFINE_EVENT_PRINT(template, name, proto, args, print) \ - DEFINE_TRACE(name) + DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) #undef DEFINE_EVENT_CONDITION #define DEFINE_EVENT_CONDITION(template, name, proto, args, cond) \ @@ -70,7 +70,7 @@ #undef DECLARE_TRACE #define DECLARE_TRACE(name, proto, args) \ - DEFINE_TRACE(name) + DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) #undef TRACE_INCLUDE #undef __TRACE_INCLUDE --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -221,6 +221,16 @@ static void *func_remove(struct tracepoi return old; } +static void tracepoint_update_call(struct tracepoint *tp, struct tracepoint_func *tp_funcs) +{ + void *func = tp->iterator; + + if (!tp_funcs[1].func) + func = tp_funcs[0].func; + + __static_call_update(tp->static_call_key, tp->static_call_tramp, func); +} + /* * Add the probe function to a tracepoint. */ @@ -251,8 +261,9 @@ static int tracepoint_add_func(struct tr * include/linux/tracepoint.h using rcu_dereference_sched(). */ rcu_assign_pointer(tp->funcs, tp_funcs); - if (!static_key_enabled(&tp->key)) - static_key_slow_inc(&tp->key); + tracepoint_update_call(tp, tp_funcs); + static_key_enable(&tp->key); + release_probes(old); return 0; } @@ -281,9 +292,11 @@ static int tracepoint_remove_func(struct if (tp->unregfunc && static_key_enabled(&tp->key)) tp->unregfunc(); - if (static_key_enabled(&tp->key)) - static_key_slow_dec(&tp->key); + static_key_disable(&tp->key); + } else { + tracepoint_update_call(tp, tp_funcs); } + rcu_assign_pointer(tp->funcs, tp_funcs); release_probes(old); return 0;