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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 754ABC4332F for ; Fri, 11 Nov 2022 14:44:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231615AbiKKOn5 (ORCPT ); Fri, 11 Nov 2022 09:43:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48970 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234743AbiKKOnO (ORCPT ); Fri, 11 Nov 2022 09:43:14 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70D6065870; Fri, 11 Nov 2022 06:41:42 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A484B61FE6; Fri, 11 Nov 2022 14:41:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5C04C433D6; Fri, 11 Nov 2022 14:41:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668177701; bh=rGEIHLPEICYwUECDm+ra1Rny+amGBJwmuk17o2juNNE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=SkCUes6m7WwfXVIdP+0DM6mr97vCnrEtSVtHkENZ284mQ+A7A04svKiUGVV/9QLgH 2ko247lGaf3veH43D6M2LI9WjC23sKj/5jF8VCd56G/udmcv/KTRjUz27BWRkH0+8n QXxPA7iHnC26EhRPjdezukpEn6Ty0eLPQdQbWLZhLCfJ0FclwnstJeYGfEIHMuzeaB WxZSrMEVTqUo5XaaxNfExx+Y9iHfEDx0wI+5VqaT46hK105nZyAM/Ji1HWhi0BTEGA ShXU+MHeY9kz/oir6xBtrSrRnTmbPx0GLxGpsr5Miccxy9At9SjGTNzO0bHuwqn4uI n2oRmvb0ZFkUQ== Date: Fri, 11 Nov 2022 23:41:37 +0900 From: Masami Hiramatsu (Google) To: Zheng Yejian Cc: , , Subject: Re: [PATCH v2] tracing: Optimize event type allocation with IDA Message-Id: <20221111234137.90d9ec624497a7e1f5cb5003@kernel.org> In-Reply-To: <20221110020319.1259291-1-zhengyejian1@huawei.com> References: <20221110020319.1259291-1-zhengyejian1@huawei.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 10 Nov 2022 10:03:19 +0800 Zheng Yejian wrote: > After commit 060fa5c83e67 ("tracing/events: reuse trace event ids after > overflow"), trace events with dynamic type are linked up in list > 'ftrace_event_list' through field 'trace_event.list'. Then when max > event type number used up, it's possible to reuse type number of some > freed one by traversing 'ftrace_event_list'. > > As instead, using IDA to manage available type numbers can make codes > simpler and then the field 'trace_event.list' can be dropped. > > Since 'struct trace_event' is used in static tracepoints, drop > 'trace_event.list' can make vmlinux smaller. Local test with about 2000 > tracepoints, vmlinux reduced about 64KB: > before：-rwxrwxr-x 1 root root 76669448 Nov 8 17:14 vmlinux > after： -rwxrwxr-x 1 root root 76604176 Nov 8 17:15 vmlinux > This looks good to me. Acked-by: Masami Hiramatsu (Google) Thanks > Signed-off-by: Zheng Yejian > --- > include/linux/trace_events.h | 1 - > kernel/trace/trace_output.c | 66 +++++++++--------------------------- > 2 files changed, 16 insertions(+), 51 deletions(-) > > Changes since v1: > - Explicitly include linux/idr.h as suggested by Masami Hiramatsu > Link: https://lore.kernel.org/lkml/20221109222650.ce6c22e231345f6852f6956f@kernel.org/#t > > diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h > index 20749bd9db71..bb2053246d6a 100644 > --- a/include/linux/trace_events.h > +++ b/include/linux/trace_events.h > @@ -136,7 +136,6 @@ struct trace_event_functions { > > struct trace_event { > struct hlist_node node; > - struct list_head list; > int type; > struct trace_event_functions *funcs; > }; > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > index 67f47ea27921..f0ba97121345 100644 > --- a/kernel/trace/trace_output.c > +++ b/kernel/trace/trace_output.c > @@ -11,6 +11,7 @@ > #include > #include > #include > +#include > > #include "trace_output.h" > > @@ -21,8 +22,6 @@ DECLARE_RWSEM(trace_event_sem); > > static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly; > > -static int next_event_type = __TRACE_LAST_TYPE; > - > enum print_line_t trace_print_bputs_msg_only(struct trace_iterator *iter) > { > struct trace_seq *s = &iter->seq; > @@ -688,38 +687,23 @@ struct trace_event *ftrace_find_event(int type) > return NULL; > } > > -static LIST_HEAD(ftrace_event_list); > +static DEFINE_IDA(trace_event_ida); > > -static int trace_search_list(struct list_head **list) > +static void free_trace_event_type(int type) > { > - struct trace_event *e = NULL, *iter; > - int next = __TRACE_LAST_TYPE; > - > - if (list_empty(&ftrace_event_list)) { > - *list = &ftrace_event_list; > - return next; > - } > + if (type >= __TRACE_LAST_TYPE) > + ida_free(&trace_event_ida, type); > +} > > - /* > - * We used up all possible max events, > - * lets see if somebody freed one. > - */ > - list_for_each_entry(iter, &ftrace_event_list, list) { > - if (iter->type != next) { > - e = iter; > - break; > - } > - next++; > - } > +static int alloc_trace_event_type(void) > +{ > + int next; > > - /* Did we used up all 65 thousand events??? */ > - if (next > TRACE_EVENT_TYPE_MAX) > + /* Skip static defined type numbers */ > + next = ida_alloc_range(&trace_event_ida, __TRACE_LAST_TYPE, > + TRACE_EVENT_TYPE_MAX, GFP_KERNEL); > + if (next < 0) > return 0; > - > - if (e) > - *list = &e->list; > - else > - *list = &ftrace_event_list; > return next; > } > > @@ -761,28 +745,10 @@ int register_trace_event(struct trace_event *event) > if (WARN_ON(!event->funcs)) > goto out; > > - INIT_LIST_HEAD(&event->list); > - > if (!event->type) { > - struct list_head *list = NULL; > - > - if (next_event_type > TRACE_EVENT_TYPE_MAX) { > - > - event->type = trace_search_list(&list); > - if (!event->type) > - goto out; > - > - } else { > - > - event->type = next_event_type++; > - list = &ftrace_event_list; > - } > - > - if (WARN_ON(ftrace_find_event(event->type))) > + event->type = alloc_trace_event_type(); > + if (!event->type) > goto out; > - > - list_add_tail(&event->list, list); > - > } else if (WARN(event->type > __TRACE_LAST_TYPE, > "Need to add type to trace.h")) { > goto out; > @@ -819,7 +785,7 @@ EXPORT_SYMBOL_GPL(register_trace_event); > int __unregister_trace_event(struct trace_event *event) > { > hlist_del(&event->node); > - list_del(&event->list); > + free_trace_event_type(event->type); > return 0; > } > > -- > 2.25.1 > -- Masami Hiramatsu (Google)