From patchwork Sun Jun 18 08:08:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe JAILLET X-Patchwork-Id: 694322 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 16A31EB64D7 for ; Sun, 18 Jun 2023 08:08:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229456AbjFRIIP (ORCPT ); Sun, 18 Jun 2023 04:08:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229480AbjFRIIO (ORCPT ); Sun, 18 Jun 2023 04:08:14 -0400 Received: from smtp.smtpout.orange.fr (smtp-13.smtpout.orange.fr [80.12.242.13]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4BF3310F7 for ; Sun, 18 Jun 2023 01:08:12 -0700 (PDT) Received: from pop-os.home ([86.243.2.178]) by smtp.orange.fr with ESMTPA id AnSCqLxfhonlZAnSCqJfqb; Sun, 18 Jun 2023 10:08:09 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wanadoo.fr; s=t20230301; t=1687075689; bh=6WU86U56M483R8yCdnQ94w/Wv9IX0lwEV7xy79EtEyk=; h=From:To:Cc:Subject:Date; b=N36yDDgSCRkLrphXPqmm/dtSd1JNg5zw6b7jMluim6E3cM2Mo7DPbRvojniGDsKi8 Tw6UGwhlHpoil/CCQfP9b9xGo78DEAZ+jbFfSPJYFnkwe+sNLr9XORsu1zIzV0dsh5 8idwfq2cXOtQPdXM5dMvSlR2XKus3vAuC6KbMiChu1Am2VWr1GiYPRJWvUHinq8Nqx muQe+61ICsMm6NxJg2P7kGmoQndO3g88eLfvbyaayRNn8iI8IW5HKlvxbP1Gp6J3Py tSLijylbvIbIZH8eYncu53QEXmEPZBt14U68FVZ/juQ56V3k4EBqE30Z2RSmEYf+Ej YpFfIPuMpgmiA== X-ME-Helo: pop-os.home X-ME-Auth: Y2hyaXN0b3BoZS5qYWlsbGV0QHdhbmFkb28uZnI= X-ME-Date: Sun, 18 Jun 2023 10:08:09 +0200 X-ME-IP: 86.243.2.178 From: Christophe JAILLET To: Jiri Kosina , Benjamin Tissoires Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Christophe JAILLET , linux-input@vger.kernel.org Subject: [PATCH] HID: Reorder fields in 'struct hid_field' Date: Sun, 18 Jun 2023 10:08:07 +0200 Message-Id: X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org Group some variables based on their sizes to reduce hole and avoid padding. On x86_64, this shrinks the size of 'struct hid_field' from 136 to 128 bytes. It saves a few bytes of memory and is more cache-line friendly. Signed-off-by: Christophe JAILLET --- Using pahole Before: ====== struct hid_field { unsigned int physical; /* 0 4 */ unsigned int logical; /* 4 4 */ unsigned int application; /* 8 4 */ /* XXX 4 bytes hole, try to pack */ struct hid_usage * usage; /* 16 8 */ unsigned int maxusage; /* 24 4 */ unsigned int flags; /* 28 4 */ unsigned int report_offset; /* 32 4 */ unsigned int report_size; /* 36 4 */ unsigned int report_count; /* 40 4 */ unsigned int report_type; /* 44 4 */ __s32 * value; /* 48 8 */ __s32 * new_value; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ __s32 * usages_priorities; /* 64 8 */ __s32 logical_minimum; /* 72 4 */ __s32 logical_maximum; /* 76 4 */ __s32 physical_minimum; /* 80 4 */ __s32 physical_maximum; /* 84 4 */ __s32 unit_exponent; /* 88 4 */ unsigned int unit; /* 92 4 */ bool ignored; /* 96 1 */ /* XXX 7 bytes hole, try to pack */ struct hid_report * report; /* 104 8 */ unsigned int index; /* 112 4 */ /* XXX 4 bytes hole, try to pack */ struct hid_input * hidinput; /* 120 8 */ /* --- cacheline 2 boundary (128 bytes) --- */ __u16 dpad; /* 128 2 */ /* XXX 2 bytes hole, try to pack */ unsigned int slot_idx; /* 132 4 */ /* size: 136, cachelines: 3, members: 25 */ /* sum members: 119, holes: 4, sum holes: 17 */ /* last cacheline: 8 bytes */ }; After: ===== struct hid_field { unsigned int physical; /* 0 4 */ unsigned int logical; /* 4 4 */ unsigned int application; /* 8 4 */ /* XXX 4 bytes hole, try to pack */ struct hid_usage * usage; /* 16 8 */ unsigned int maxusage; /* 24 4 */ unsigned int flags; /* 28 4 */ unsigned int report_offset; /* 32 4 */ unsigned int report_size; /* 36 4 */ unsigned int report_count; /* 40 4 */ unsigned int report_type; /* 44 4 */ __s32 * value; /* 48 8 */ __s32 * new_value; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ __s32 * usages_priorities; /* 64 8 */ __s32 logical_minimum; /* 72 4 */ __s32 logical_maximum; /* 76 4 */ __s32 physical_minimum; /* 80 4 */ __s32 physical_maximum; /* 84 4 */ __s32 unit_exponent; /* 88 4 */ unsigned int unit; /* 92 4 */ struct hid_report * report; /* 96 8 */ unsigned int index; /* 104 4 */ bool ignored; /* 108 1 */ /* XXX 3 bytes hole, try to pack */ struct hid_input * hidinput; /* 112 8 */ __u16 dpad; /* 120 2 */ /* XXX 2 bytes hole, try to pack */ unsigned int slot_idx; /* 124 4 */ /* size: 128, cachelines: 2, members: 25 */ /* sum members: 119, holes: 3, sum holes: 9 */ }; --- include/linux/hid.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/hid.h b/include/linux/hid.h index 39e21e3815ad..5be5e671c263 100644 --- a/include/linux/hid.h +++ b/include/linux/hid.h @@ -480,9 +480,9 @@ struct hid_field { __s32 physical_maximum; __s32 unit_exponent; unsigned unit; - bool ignored; /* this field is ignored in this event */ struct hid_report *report; /* associated report */ unsigned index; /* index into report->field[] */ + bool ignored; /* this field is ignored in this event */ /* hidinput data */ struct hid_input *hidinput; /* associated input structure */ __u16 dpad; /* dpad input code */