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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham 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 20280C32789 for ; Sun, 4 Nov 2018 19:26:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CBBF82082E for ; Sun, 4 Nov 2018 19:26:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CBBF82082E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729417AbeKEEmY (ORCPT ); Sun, 4 Nov 2018 23:42:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41720 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728970AbeKEEmY (ORCPT ); Sun, 4 Nov 2018 23:42:24 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8EA5D308421A; Sun, 4 Nov 2018 19:26:19 +0000 (UTC) Received: from krava (ovpn-204-66.brq.redhat.com [10.40.204.66]) by smtp.corp.redhat.com (Postfix) with SMTP id 0838719749; Sun, 4 Nov 2018 19:26:16 +0000 (UTC) Date: Sun, 4 Nov 2018 20:26:15 +0100 From: Jiri Olsa To: Rasmus Villemoes Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Namhyung Kim , linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf: replace automatic const char[] variables by statics Message-ID: <20181104192615.GC18517@krava> References: <20181102230624.20064-1-linux@rasmusvillemoes.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181102230624.20064-1-linux@rasmusvillemoes.dk> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Sun, 04 Nov 2018 19:26:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Nov 03, 2018 at 12:06:23AM +0100, Rasmus Villemoes wrote: > An automatic const char[] variable gets initialized at runtime, just > like any other automatic variable. For long strings, that uses a lot of > stack and wastes time building the string; e.g. for the "No %s > allocation events..." case one has > > 444516: 48 b8 4e 6f 20 25 73 20 61 6c movabs $0x6c61207325206f4e,%rax # "No %s al" > ... > 444674: 48 89 45 80 mov %rax,-0x80(%rbp) > 444678: 48 b8 6c 6f 63 61 74 69 6f 6e movabs $0x6e6f697461636f6c,%rax # "location" > 444682: 48 89 45 88 mov %rax,-0x78(%rbp) > 444686: 48 b8 20 65 76 65 6e 74 73 20 movabs $0x2073746e65766520,%rax # " events " > 444690: 66 44 89 55 c4 mov %r10w,-0x3c(%rbp) > 444695: 48 89 45 90 mov %rax,-0x70(%rbp) > 444699: 48 b8 66 6f 75 6e 64 2e 20 20 movabs $0x20202e646e756f66,%rax > > Make them all static so that the compiler just references objects in .rodata. > > Signed-off-by: Rasmus Villemoes sounds good Acked-by: Jiri Olsa thanks, jirka > --- > tools/perf/builtin-c2c.c | 4 ++-- > tools/perf/builtin-kmem.c | 4 ++-- > tools/perf/builtin-report.c | 6 +++--- > tools/perf/builtin-sched.c | 2 +- > tools/perf/ui/browsers/header.c | 2 +- > tools/perf/ui/browsers/hists.c | 4 ++-- > 6 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c > index f3aa9d02a5ab..ab6a89e5393c 100644 > --- a/tools/perf/builtin-c2c.c > +++ b/tools/perf/builtin-c2c.c > @@ -2343,7 +2343,7 @@ static int perf_c2c__browse_cacheline(struct hist_entry *he) > struct c2c_cacheline_browser *cl_browser; > struct hist_browser *browser; > int key = -1; > - const char help[] = > + static const char help[] = > " ENTER Toggle callchains (if present) \n" > " n Toggle Node details info \n" > " s Toggle full length of symbol and source line columns \n" > @@ -2424,7 +2424,7 @@ static int perf_c2c__hists_browse(struct hists *hists) > { > struct hist_browser *browser; > int key = -1; > - const char help[] = > + static const char help[] = > " d Display cacheline details \n" > " ENTER Toggle callchains (if present) \n" > " q Quit \n"; > diff --git a/tools/perf/builtin-kmem.c b/tools/perf/builtin-kmem.c > index b63bca4b0c2a..088705c167bf 100644 > --- a/tools/perf/builtin-kmem.c > +++ b/tools/perf/builtin-kmem.c > @@ -334,7 +334,7 @@ static int build_alloc_func_list(void) > struct alloc_func *func; > struct machine *machine = &kmem_session->machines.host; > regex_t alloc_func_regex; > - const char pattern[] = "^_?_?(alloc|get_free|get_zeroed)_pages?"; > + static const char pattern[] = "^_?_?(alloc|get_free|get_zeroed)_pages?"; > > ret = regcomp(&alloc_func_regex, pattern, REG_EXTENDED); > if (ret) { > @@ -1924,7 +1924,7 @@ int cmd_kmem(int argc, const char **argv) > NULL > }; > struct perf_session *session; > - const char errmsg[] = "No %s allocation events found. Have you run 'perf kmem record --%s'?\n"; > + static const char errmsg[] = "No %s allocation events found. Have you run 'perf kmem record --%s'?\n"; > int ret = perf_config(kmem_config, NULL); > > if (ret) > diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c > index 257c9c18cb7e..ff615c624784 100644 > --- a/tools/perf/builtin-report.c > +++ b/tools/perf/builtin-report.c > @@ -955,9 +955,9 @@ int cmd_report(int argc, const char **argv) > int branch_mode = -1; > bool branch_call_mode = false; > #define CALLCHAIN_DEFAULT_OPT "graph,0.5,caller,function,percent" > - const char report_callchain_help[] = "Display call graph (stack chain/backtrace):\n\n" > - CALLCHAIN_REPORT_HELP > - "\n\t\t\t\tDefault: " CALLCHAIN_DEFAULT_OPT; > + static const char report_callchain_help[] = "Display call graph (stack chain/backtrace):\n\n" > + CALLCHAIN_REPORT_HELP > + "\n\t\t\t\tDefault: " CALLCHAIN_DEFAULT_OPT; > char callchain_default_opt[] = CALLCHAIN_DEFAULT_OPT; > const char * const report_usage[] = { > "perf report []", > diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c > index cbf39dab19c1..2e0f0c65964a 100644 > --- a/tools/perf/builtin-sched.c > +++ b/tools/perf/builtin-sched.c > @@ -3336,7 +3336,7 @@ static int __cmd_record(int argc, const char **argv) > > int cmd_sched(int argc, const char **argv) > { > - const char default_sort_order[] = "avg, max, switch, runtime"; > + static const char default_sort_order[] = "avg, max, switch, runtime"; > struct perf_sched sched = { > .tool = { > .sample = perf_sched__process_tracepoint_sample, > diff --git a/tools/perf/ui/browsers/header.c b/tools/perf/ui/browsers/header.c > index d75492189acb..5aeb663dd184 100644 > --- a/tools/perf/ui/browsers/header.c > +++ b/tools/perf/ui/browsers/header.c > @@ -35,7 +35,7 @@ static int list_menu__run(struct ui_browser *menu) > { > int key; > unsigned long offset; > - const char help[] = > + static const char help[] = > "h/?/F1 Show this window\n" > "UP/DOWN/PGUP\n" > "PGDN/SPACE\n" > diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c > index a96f62ca984a..eab9dc025b3a 100644 > --- a/tools/perf/ui/browsers/hists.c > +++ b/tools/perf/ui/browsers/hists.c > @@ -2737,7 +2737,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events, > "S Zoom into current Processor Socket\n" \ > > /* help messages are sorted by lexical order of the hotkey */ > - const char report_help[] = HIST_BROWSER_HELP_COMMON > + static const char report_help[] = HIST_BROWSER_HELP_COMMON > "i Show header information\n" > "P Print histograms to perf.hist.N\n" > "r Run available scripts\n" > @@ -2745,7 +2745,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events, > "t Zoom into current Thread\n" > "V Verbose (DSO names in callchains, etc)\n" > "/ Filter symbol by name"; > - const char top_help[] = HIST_BROWSER_HELP_COMMON > + static const char top_help[] = HIST_BROWSER_HELP_COMMON > "P Print histograms to perf.hist.N\n" > "t Zoom into current Thread\n" > "V Verbose (DSO names in callchains, etc)\n" > -- > 2.19.1.6.gbde171bbf5 >