From nobody Wed Dec 17 12:19:22 2025 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 D607CC4167B for ; Mon, 27 Nov 2023 08:53:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232554AbjK0Ixc (ORCPT ); Mon, 27 Nov 2023 03:53:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55988 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232620AbjK0Ix1 (ORCPT ); Mon, 27 Nov 2023 03:53:27 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46BFC1AD; Mon, 27 Nov 2023 00:53:32 -0800 (PST) Date: Mon, 27 Nov 2023 08:53:28 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1701075209; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CHN5isM16XvAh/O16p6UY2UrydXWXhGG5EHOuvXB+54=; b=MtQMJ1H6a2LdOMsJJNFDx+X0wIfob1Wf3M7UNk37OZ1V6GNWb4MqgkGRgM2elBC8cNqMNe 7O6qhes0/CoMu1SuFsvnVMzLlLxDxlqlGM5prwNBo64gdueolhQBvLJcVhFD5+qFdwqUfx VbyVIX/Au3kjhmDFcsvsL6IHlGBkoCOVa0AmrzIa1vO65Y8O3pHKelUwp/U7EnFiDJNPTL pvtCf9zCcFjO/j0vcqMZV6Hyl28jU9NAP7x6lUc1poQfJe2kGAbKwWsuPueQ98tQTFSRYK MAAk/gkcStajqEiuRTzgW2jHGbhGXQTGId559LfJB0c8Ple8u6HvYNXgJhxa8g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1701075209; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CHN5isM16XvAh/O16p6UY2UrydXWXhGG5EHOuvXB+54=; b=dwht2BZCsIGKQxzbLxnVHi6/b6j2Xc3MyKMnyEcI0dK3UUIhZM6h08q8+bDMmKQcYe1R1s GvttdcmQDxFmcFBg== From: "tip-bot2 for Christophe JAILLET" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] locking/lockdep: Slightly reorder 'struct lock_class' to save some memory Cc: Christophe JAILLET , Ingo Molnar , Waiman Long , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: =?utf-8?q?=3C801258371fc4101f96495a5aaecef638d6cbd8d3=2E17009?= =?utf-8?q?88869=2Egit=2Echristophe=2Ejaillet=40wanadoo=2Efr=3E?= References: =?utf-8?q?=3C801258371fc4101f96495a5aaecef638d6cbd8d3=2E170098?= =?utf-8?q?8869=2Egit=2Echristophe=2Ejaillet=40wanadoo=2Efr=3E?= MIME-Version: 1.0 Message-ID: <170107520853.398.5812171619911841670.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the locking/core branch of tip: Commit-ID: 18caaedaf4c3712ab6821f292598a8f86e6d7972 Gitweb: https://git.kernel.org/tip/18caaedaf4c3712ab6821f292598a8f86= e6d7972 Author: Christophe JAILLET AuthorDate: Sun, 26 Nov 2023 09:56:29 +01:00 Committer: Ingo Molnar CommitterDate: Mon, 27 Nov 2023 09:46:52 +01:00 locking/lockdep: Slightly reorder 'struct lock_class' to save some memory Based on pahole, 2 holes can be combined in the 'struct lock_class'. This saves 8 bytes in the structure on my x86_64. On a x86_64 configured with allmodconfig, this saves ~64kb of memory in 'kernel/locking/lockdep.o': text data bss dec filename Before: 102,501 1,912,490 11,531,636 13,546,627 kernel/lo= cking/lockdep.o After: 102,181 1,912,490 11,466,100 13,480,771 kernel/lo= cking/lockdep.o because of: struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; After the reorder, pahole gives: struct lock_class { struct hlist_node hash_entry; /* 0 16 */ struct list_head lock_entry; /* 16 16 */ struct list_head locks_after; /* 32 16 */ struct list_head locks_before; /* 48 16 */ /* --- cacheline 1 boundary (64 bytes) --- */ const struct lockdep_subclass_key * key; /* 64 8 */ lock_cmp_fn cmp_fn; /* 72 8 */ lock_print_fn print_fn; /* 80 8 */ unsigned int subclass; /* 88 4 */ unsigned int dep_gen_id; /* 92 4 */ long unsigned int usage_mask; /* 96 8 */ const struct lock_trace * usage_traces[10]; /* 104 80 */ /* --- cacheline 2 boundary (128 bytes) was 56 bytes ago --- */ const char * name; /* 184 8 */ /* --- cacheline 3 boundary (192 bytes) --- */ int name_version; /* 192 4 */ u8 wait_type_inner; /* 196 1 */ u8 wait_type_outer; /* 197 1 */ u8 lock_type; /* 198 1 */ /* XXX 1 byte hole, try to pack */ long unsigned int contention_point[4]; /* 200 32 */ long unsigned int contending_point[4]; /* 232 32 */ /* size: 264, cachelines: 5, members: 18 */ /* sum members: 263, holes: 1, sum holes: 1 */ /* last cacheline: 8 bytes */ }; Signed-off-by: Christophe JAILLET Signed-off-by: Ingo Molnar Acked-by: Waiman Long Link: https://lore.kernel.org/r/801258371fc4101f96495a5aaecef638d6cbd8d3.17= 00988869.git.christophe.jaillet@wanadoo.fr --- include/linux/lockdep_types.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/lockdep_types.h b/include/linux/lockdep_types.h index 2ebc323..857d785 100644 --- a/include/linux/lockdep_types.h +++ b/include/linux/lockdep_types.h @@ -127,12 +127,12 @@ struct lock_class { unsigned long usage_mask; const struct lock_trace *usage_traces[LOCK_TRACE_STATES]; =20 + const char *name; /* * Generation counter, when doing certain classes of graph walking, * to ensure that we check one node only once: */ int name_version; - const char *name; =20 u8 wait_type_inner; u8 wait_type_outer;