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 D8C54C197A0 for ; Thu, 16 Nov 2023 12:42:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345158AbjKPMm1 (ORCPT ); Thu, 16 Nov 2023 07:42:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345142AbjKPMm0 (ORCPT ); Thu, 16 Nov 2023 07:42:26 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE60F193 for ; Thu, 16 Nov 2023 04:42:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700138540; h=from:from: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=h0cgDtlCn3yVws2N/gdlQc9Ry1b50ay82U2VPVFHUd8=; b=eTZ5IJOL0qAyuOJeSlxvzvw2IUHYPSwyYhHinJk+s3VcnNXOAPE9T+GmP29nI856npIAA2 Bfi99OYSwcPBXpq044zEiJdMwZkUMfh+J/h5l1TZvocDUnc0O82biZdPAZgSsnPeyzU9Mu NeoRMN2rNn3q1X7RvrwhGm7/omg7Z8U= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-210-cunVPJq3M0ikTpkJFsMo_w-1; Thu, 16 Nov 2023 07:42:17 -0500 X-MC-Unique: cunVPJq3M0ikTpkJFsMo_w-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 15A2B8058ED; Thu, 16 Nov 2023 12:42:17 +0000 (UTC) Received: from [10.22.16.205] (unknown [10.22.16.205]) by smtp.corp.redhat.com (Postfix) with ESMTP id C95041C060B5; Thu, 16 Nov 2023 12:42:16 +0000 (UTC) Message-ID: Date: Thu, 16 Nov 2023 07:42:16 -0500 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] lockdep: optimise "struct lock_class" layout Content-Language: en-US To: Alexey Dobriyan , Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng Cc: linux-kernel@vger.kernel.org References: From: Waiman Long In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/16/23 06:25, Alexey Dobriyan wrote: > struct lock_class does > > const struct lock_trace * usage_traces[]; > int name_version; > const char * name; > > which wastes 4 bytes after "name_version". > > Put pointer after pointers shrinking sizeof from 208 bytes to 200 bytes. > Space savings are considerable for such a trivial patch: > > $ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux > add/remove: 0/0 grow/shrink: 1/11 up/down: 2/-65640 (-65638) > Function old new delta > check_irq_usage 2852 2854 +2 > reacquire_held_locks 486 484 -2 > lock_chain_get_class 41 39 -2 > l_start 34 32 -2 > check_noncircular 276 274 -2 > print_usage_bug.part 688 683 -5 > print_circular_bug 1017 1011 -6 > hlock_conflict 141 135 -6 > print_deadlock_bug 944 935 -9 > mark_lock 3791 3769 -22 > __lock_acquire 9801 9753 -48 > lock_classes 1703936 1638400 -65536 > Total: Before=21163908, After=21098270, chg -0.31% > > Signed-off-by: Alexey Dobriyan > --- > > include/linux/lockdep_types.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- 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]; > > + 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; > > u8 wait_type_inner; > u8 wait_type_outer; > LGTM. Acked-by: Waiman Long