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=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,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 4E82CC04AAA for ; Mon, 6 May 2019 08:20:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2216E20C01 for ; Mon, 6 May 2019 08:20:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hvsUWLx4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726728AbfEFIU4 (ORCPT ); Mon, 6 May 2019 04:20:56 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:38814 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726648AbfEFIUx (ORCPT ); Mon, 6 May 2019 04:20:53 -0400 Received: by mail-pf1-f195.google.com with SMTP id 10so6355802pfo.5 for ; Mon, 06 May 2019 01:20:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=r6Ul8DqLCrwUzW/73FoDcrnG9o+ApspVb0NBeqVAdd8=; b=hvsUWLx42A+WRy5nb3rtkdmvbL88ClAOBumICvHHENL9aBosAJJvsojy2mJkQgLe/i PJOM51rfzWErur+UtjhVQgkwvI4fvVvtX328WwrFda5xsP/rPA14X7UlH8tmJTEKV5IC FVvynx1zFzjcq4u80+/T/Ed40SjJFKCZMnk1rvcosqj8TRSYJMpunekTAP9c3XKPQRIx 3PJGz1dklrRr4fq5NrS3W3dvvCsskEEG5EQvPvuikNN4JLXpkHPwak5BBYuToi2BeJ82 yAJTJH7uQeSmeuZFBu1TBNXOcDLETwCA+IoMrdMkwnjfhF4mzfUFJapMcvOoGK7s37rz N5cw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=r6Ul8DqLCrwUzW/73FoDcrnG9o+ApspVb0NBeqVAdd8=; b=ViDJhTs8KSuHwoDDwQXimcu0Z8fC0ovZZOd4quAcqnoD/62X6hwLzjQhNyaApma/sf P3iuh9Moo2PR+F4lz/M51qWQwzcm66LaTDPaW4444bEJQGwptyYBra2y9iAKQAU0NSxl 6Mip++InC7UCuUXSrSelp3+Qfx53MjcLzrOXDiR2ZFHfjZ2FKpcsxGqVEZWCS8bZU3HO 9vF/mNweoSimU2E9+MLFhR7OFmp1MOU0Qa3BGDlAs/h3gplsiQGutiKyNcWq/mssoXlk pMp4bMZwgZK8FVbpDrG+7lk0j50zX0ftBQMswbHGtuJWYn4Mch0dLypz5TSKC0xTNNO8 cPNg== X-Gm-Message-State: APjAAAX2aVE2hQ74JGHuQhIkxSVvgkJ5qZNnhsNobOBkUHssV/lm6Hiz q1k7k5BcTn72oOpq3J0r28Q= X-Google-Smtp-Source: APXvYqz4o2SPXUcSTdbu7daT3P7D16Mm9N/Qg38znPGo6ijgAtTye/zW+Mjd0ZciiLiHsNEUVMNKMg== X-Received: by 2002:a62:4c5:: with SMTP id 188mr32120914pfe.29.1557130852698; Mon, 06 May 2019 01:20:52 -0700 (PDT) Received: from localhost.localdomain ([203.100.54.194]) by smtp.gmail.com with ESMTPSA id v19sm20958013pfa.138.2019.05.06.01.20.49 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 06 May 2019 01:20:52 -0700 (PDT) From: Yuyang Du To: peterz@infradead.org, will.deacon@arm.com, mingo@kernel.org Cc: bvanassche@acm.org, ming.lei@redhat.com, frederic@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, Yuyang Du Subject: [PATCH v2 20/23] locking/lockdep: Check redundant dependency only when CONFIG_LOCKDEP_SMALL Date: Mon, 6 May 2019 16:19:36 +0800 Message-Id: <20190506081939.74287-21-duyuyang@gmail.com> X-Mailer: git-send-email 2.20.1 (Apple Git-117) In-Reply-To: <20190506081939.74287-1-duyuyang@gmail.com> References: <20190506081939.74287-1-duyuyang@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As Peter has put it all sound and complete for the cause, I simply quote: "It (check_redundant) was added for cross-release (which has since been reverted) which would generate a lot of redundant links (IIRC) but having it makes the reports more convoluted -- basically, if we had an A-B-C relation, then A-C will not be added to the graph because it is already covered. This then means any report will include B, even though a shorter cycle might have been possible." This would increase the number of direct dependencies. For a simple workload (make clean; reboot; make vmlinux -j8), the data looks like this: CONFIG_LOCKDEP_SMALL: direct dependencies: 6926 !CONFIG_LOCKDEP_SMALL: direct dependencies: 9052 (+30.7%) Suggested-by: Peter Zijlstra (Intel) Signed-off-by: Yuyang Du --- kernel/locking/lockdep.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 2502ea4..9d2728c 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1734,6 +1734,7 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) return ret; } +#ifdef CONFIG_LOCKDEP_SMALL /* * Check that the dependency graph starting at can lead to * or not. If it can, -> dependency is already @@ -1763,6 +1764,7 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) return ret; } +#endif #ifdef CONFIG_TRACE_IRQFLAGS @@ -2423,12 +2425,14 @@ static inline void inc_chains(void) } } +#ifdef CONFIG_LOCKDEP_SMALL /* * Is the -> link redundant? */ ret = check_redundant(prev, next); if (ret != 1) return ret; +#endif if (!trace->nr_entries && !save_trace(trace)) return 0; -- 1.8.3.1