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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT 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 3A162C433EF for ; Sat, 11 Sep 2021 13:51:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1298D61209 for ; Sat, 11 Sep 2021 13:51:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235977AbhIKNwd (ORCPT ); Sat, 11 Sep 2021 09:52:33 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:45506 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235934AbhIKNwb (ORCPT ); Sat, 11 Sep 2021 09:52:31 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=yinan@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0Uo-bker_1631368273; Received: from localhost(mailfrom:yinan@linux.alibaba.com fp:SMTPD_---0Uo-bker_1631368273) by smtp.aliyun-inc.com(127.0.0.1); Sat, 11 Sep 2021 21:51:17 +0800 From: Yinan Liu To: yinan@linux.alibaba.com, rostedt@goodmis.org, mark-pk.tsai@mediatek.com, peterz@infradead.org, mingo@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] scripts: ftrace - move the nop-processing in ftrace_init to compile time Date: Sat, 11 Sep 2021 21:50:43 +0800 Message-Id: <20210911135043.16014-3-yinan@linux.alibaba.com> X-Mailer: git-send-email 2.14.4.44.g2045bb6 In-Reply-To: <20210911135043.16014-1-yinan@linux.alibaba.com> References: <20210911135043.16014-1-yinan@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When ftrace is enabled, ftrace_init will consume a period of time, usually around 15~20ms. Approximately 60% of the time is consumed by nop-processing. Moving the nop-processing to the compile time can speed up the kernel boot process. performance test: env: Intel(R) Xeon(R) CPU E5-2682 v4 @ 2.50GHz method: before and after patching, compare the total time of ftrace_init(), and verify the functionality of ftrace. avg_time of ftrace_init: with patch: 7.114ms without patch: 15.763ms Signed-off-by: Yinan Liu --- kernel/trace/ftrace.c | 4 ++++ scripts/recordmcount.h | 14 ++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index c236da868990..ae3fba331179 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6261,6 +6261,10 @@ static int ftrace_process_locs(struct module *mod, * until we are finished with it, and there's no * reason to cause large interrupt latencies while we do it. */ +#if defined CONFIG_X86 || defined CONFIG_X86_64 || defined CONFIG_ARM || defined CONFIG_ARM64 + ret = 0; + goto out; +#endif if (!mod) local_irq_save(flags); ftrace_update_code(mod, start_pg); diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h index 1e9baa5c4fc6..152311639a0b 100644 --- a/scripts/recordmcount.h +++ b/scripts/recordmcount.h @@ -406,6 +406,8 @@ static uint_t *sift_rel_mcount(uint_t *mlocp, uint_t const recval, unsigned const reltype) { + Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff) + (void *)ehdr); + Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)]; uint_t *const mloc0 = mlocp; Elf_Rel *mrelp = *mrelpp; Elf_Sym const *sym0; @@ -419,6 +421,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp, get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp); for (t = nrel; t; --t) { + int ret = -1; if (!mcountsym) mcountsym = get_mcountsym(sym0, relp, str0); @@ -436,6 +439,17 @@ static uint_t *sift_rel_mcount(uint_t *mlocp, *mlocp++ = addend; mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp); + /* convert mcount into nop */ + if (make_nop) + ret = make_nop((void *)ehdr, + _w(shdr->sh_offset) + _w(relp->r_offset)); + if (!ret) { + Elf_Rel rel; + rel = *(Elf_Rel *)relp; + Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop); + ulseek(fd_map, (void *)relp - (void *)ehdr, SEEK_SET); + uwrite(fd_map, &rel, sizeof(rel)); + } } relp = (Elf_Rel const *)(rel_entsize + (void *)relp); } -- 2.14.4.44.g2045bb6