From nobody Fri Sep 12 02:27:56 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 9DF76C05027 for ; Tue, 14 Feb 2023 08:59:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231288AbjBNI73 (ORCPT ); Tue, 14 Feb 2023 03:59:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231485AbjBNI7Z (ORCPT ); Tue, 14 Feb 2023 03:59:25 -0500 Received: from smtp.smtpout.orange.fr (smtp-28.smtpout.orange.fr [80.12.242.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 736CC23131 for ; Tue, 14 Feb 2023 00:59:05 -0800 (PST) Received: from pop-os.home ([86.243.2.178]) by smtp.orange.fr with ESMTPA id Rr9TpP4Ql5qOuRr9TpVthu; Tue, 14 Feb 2023 09:59:04 +0100 X-ME-Helo: pop-os.home X-ME-Auth: Y2hyaXN0b3BoZS5qYWlsbGV0QHdhbmFkb28uZnI= X-ME-Date: Tue, 14 Feb 2023 09:59:04 +0100 X-ME-IP: 86.243.2.178 From: Christophe JAILLET To: Lee Jones Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Christophe JAILLET Subject: [PATCH] mfd: core: Reorder fields in 'struct mfd_cell' to save some memory Date: Tue, 14 Feb 2023 09:58:59 +0100 Message-Id: X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Group some variables based on their sizes to reduce hole and avoid padding. On x86_64, this shrinks the size from 144 to 128 bytes. As an example: $ size drivers/mfd/as3722.o (Before) text data bss dec hex filename 9441 680 16 10137 2799 drivers/mfd/as3722.o $ size drivers/mfd/as3722.o (After) text data bss dec hex filename 9345 680 16 10041 2739 drivers/mfd/as3722.o Signed-off-by: Christophe JAILLET --- Using pahole Before: =3D=3D=3D=3D=3D=3D struct mfd_cell { const char * name; /* 0 8 */ int id; /* 8 4 */ int level; /* 12 4 */ int (*enable)(struct platform_device *); /* 16 = 8 */ int (*disable)(struct platform_device *); /* 24 = 8 */ int (*suspend)(struct platform_device *); /* 32 = 8 */ int (*resume)(struct platform_device *); /* 40 = 8 */ void * platform_data; /* 48 8 */ size_t pdata_size; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ const struct software_node * swnode; /* 64 8 */ const char * of_compatible; /* 72 8 */ const u64 of_reg; /* 80 8 */ bool use_of_reg; /* 88 1 */ /* XXX 7 bytes hole, try to pack */ const struct mfd_cell_acpi_match * acpi_match; /* 96 8 */ int num_resources; /* 104 4 */ /* XXX 4 bytes hole, try to pack */ const struct resource * resources; /* 112 8 */ bool ignore_resource_conflicts; /* 120 1 */ bool pm_runtime_no_callbacks; /* 121 1 */ /* XXX 6 bytes hole, try to pack */ /* --- cacheline 2 boundary (128 bytes) --- */ const char * const * parent_supplies; /* 128 8 */ int num_parent_supplies; /* 136 4 */ /* size: 144, cachelines: 3, members: 20 */ /* sum members: 123, holes: 3, sum holes: 17 */ /* padding: 4 */ /* last cacheline: 16 bytes */ }; After: =3D=3D=3D=3D=3D struct mfd_cell { const char * name; /* 0 8 */ int id; /* 8 4 */ int level; /* 12 4 */ int (*enable)(struct platform_device *); /* 16 = 8 */ int (*disable)(struct platform_device *); /* 24 = 8 */ int (*suspend)(struct platform_device *); /* 32 = 8 */ int (*resume)(struct platform_device *); /* 40 = 8 */ void * platform_data; /* 48 8 */ size_t pdata_size; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ const struct mfd_cell_acpi_match * acpi_match; /* 64 8 */ const struct software_node * swnode; /* 72 8 */ const char * of_compatible; /* 80 8 */ const u64 of_reg; /* 88 8 */ bool use_of_reg; /* 96 1 */ /* XXX 3 bytes hole, try to pack */ int num_resources; /* 100 4 */ const struct resource * resources; /* 104 8 */ bool ignore_resource_conflicts; /* 112 1 */ bool pm_runtime_no_callbacks; /* 113 1 */ /* XXX 2 bytes hole, try to pack */ int num_parent_supplies; /* 116 4 */ const char * const * parent_supplies; /* 120 8 */ /* size: 128, cachelines: 2, members: 20 */ /* sum members: 123, holes: 2, sum holes: 5 */ }; --- include/linux/mfd/core.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h index 14ca7b471576..fc4a0e9fb3bb 100644 --- a/include/linux/mfd/core.h +++ b/include/linux/mfd/core.h @@ -78,6 +78,9 @@ struct mfd_cell { void *platform_data; size_t pdata_size; =20 + /* Matches ACPI */ + const struct mfd_cell_acpi_match *acpi_match; + /* Software node for the device. */ const struct software_node *swnode; =20 @@ -97,9 +100,6 @@ struct mfd_cell { /* Set to 'true' to use 'of_reg' (above) - allows for of_reg=3D0 */ bool use_of_reg; =20 - /* Matches ACPI */ - const struct mfd_cell_acpi_match *acpi_match; - /* * These resources can be specified relative to the parent device. * For accessing hardware you should use resources from the platform dev @@ -119,8 +119,8 @@ struct mfd_cell { /* A list of regulator supplies that should be mapped to the MFD * device rather than the child device when requested */ - const char * const *parent_supplies; int num_parent_supplies; + const char * const *parent_supplies; }; =20 /* --=20 2.34.1