From patchwork Tue Feb 14 10:34:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe JAILLET X-Patchwork-Id: 13139816 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 CED46C61DA4 for ; Tue, 14 Feb 2023 10:35:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231492AbjBNKe7 (ORCPT ); Tue, 14 Feb 2023 05:34:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232577AbjBNKe6 (ORCPT ); Tue, 14 Feb 2023 05:34:58 -0500 Received: from smtp.smtpout.orange.fr (smtp-21.smtpout.orange.fr [80.12.242.21]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A89A222F8 for ; Tue, 14 Feb 2023 02:34:56 -0800 (PST) Received: from pop-os.home ([86.243.2.178]) by smtp.orange.fr with ESMTPA id RseEpCV6Kar8pRseEpAfEj; Tue, 14 Feb 2023 11:34:54 +0100 X-ME-Helo: pop-os.home X-ME-Auth: Y2hyaXN0b3BoZS5qYWlsbGV0QHdhbmFkb28uZnI= X-ME-Date: Tue, 14 Feb 2023 11:34:54 +0100 X-ME-IP: 86.243.2.178 From: Christophe JAILLET To: Mark Brown , Richard Cochran Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Christophe JAILLET , linux-spi@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH] spi: Reorder fields in 'struct spi_transfer' Date: Tue, 14 Feb 2023 11:34:50 +0100 Message-Id: <93a051da85a895bc6003aedfb00a13e1c2fc6338.1676370870.git.christophe.jaillet@wanadoo.fr> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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. Turn 'timestamped' into a bitfield so that it can be easily merged with some other bifields and move 'error'. This should have no real impact on memory allocation because 'struct spi_transfer' is mostly used on stack, but it can save a few cycles when the structure is initialized or copied. Signed-off-by: Christophe JAILLET --- Using pahole Before: ====== struct spi_transfer { const void * tx_buf; /* 0 8 */ void * rx_buf; /* 8 8 */ unsigned int len; /* 16 4 */ /* XXX 4 bytes hole, try to pack */ dma_addr_t tx_dma; /* 24 8 */ dma_addr_t rx_dma; /* 32 8 */ struct sg_table tx_sg; /* 40 16 */ struct sg_table rx_sg; /* 56 16 */ /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */ unsigned int dummy_data:1; /* 72: 0 4 */ unsigned int cs_off:1; /* 72: 1 4 */ unsigned int cs_change:1; /* 72: 2 4 */ unsigned int tx_nbits:3; /* 72: 3 4 */ unsigned int rx_nbits:3; /* 72: 6 4 */ /* XXX 7 bits hole, try to pack */ /* Bitfield combined with next fields */ u8 bits_per_word; /* 74 1 */ /* XXX 1 byte hole, try to pack */ struct spi_delay delay; /* 76 4 */ /* XXX last struct has 1 byte of padding */ struct spi_delay cs_change_delay; /* 80 4 */ /* XXX last struct has 1 byte of padding */ struct spi_delay word_delay; /* 84 4 */ /* XXX last struct has 1 byte of padding */ u32 speed_hz; /* 88 4 */ u32 effective_speed_hz; /* 92 4 */ unsigned int ptp_sts_word_pre; /* 96 4 */ unsigned int ptp_sts_word_post; /* 100 4 */ struct ptp_system_timestamp * ptp_sts; /* 104 8 */ bool timestamped; /* 112 1 */ /* XXX 7 bytes hole, try to pack */ struct list_head transfer_list; /* 120 16 */ /* --- cacheline 2 boundary (128 bytes) was 8 bytes ago --- */ u16 error; /* 136 2 */ /* size: 144, cachelines: 3, members: 24 */ /* sum members: 124, holes: 3, sum holes: 12 */ /* sum bitfield members: 9 bits, bit holes: 1, sum bit holes: 7 bits */ /* padding: 6 */ /* paddings: 3, sum paddings: 3 */ /* last cacheline: 16 bytes */ }; After: ===== struct spi_transfer { const void * tx_buf; /* 0 8 */ void * rx_buf; /* 8 8 */ unsigned int len; /* 16 4 */ u16 error; /* 20 2 */ /* XXX 2 bytes hole, try to pack */ dma_addr_t tx_dma; /* 24 8 */ dma_addr_t rx_dma; /* 32 8 */ struct sg_table tx_sg; /* 40 16 */ struct sg_table rx_sg; /* 56 16 */ /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */ unsigned int dummy_data:1; /* 72: 0 4 */ unsigned int cs_off:1; /* 72: 1 4 */ unsigned int cs_change:1; /* 72: 2 4 */ unsigned int tx_nbits:3; /* 72: 3 4 */ unsigned int rx_nbits:3; /* 72: 6 4 */ unsigned int timestamped:1; /* 72: 9 4 */ /* XXX 6 bits hole, try to pack */ /* Bitfield combined with next fields */ u8 bits_per_word; /* 74 1 */ /* XXX 1 byte hole, try to pack */ struct spi_delay delay; /* 76 4 */ /* XXX last struct has 1 byte of padding */ struct spi_delay cs_change_delay; /* 80 4 */ /* XXX last struct has 1 byte of padding */ struct spi_delay word_delay; /* 84 4 */ /* XXX last struct has 1 byte of padding */ u32 speed_hz; /* 88 4 */ u32 effective_speed_hz; /* 92 4 */ unsigned int ptp_sts_word_pre; /* 96 4 */ unsigned int ptp_sts_word_post; /* 100 4 */ struct ptp_system_timestamp * ptp_sts; /* 104 8 */ struct list_head transfer_list; /* 112 16 */ /* size: 128, cachelines: 2, members: 24 */ /* sum members: 123, holes: 2, sum holes: 3 */ /* sum bitfield members: 10 bits, bit holes: 1, sum bit holes: 6 bits */ /* paddings: 3, sum paddings: 3 */ }; --- drivers/spi/spi.c | 2 +- include/linux/spi/spi.h | 9 ++++----- 2 files changed, 5 insertions(+), 6 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 9f5c6b9f5135..44b85a8d47f1 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1927,7 +1927,7 @@ void spi_take_timestamp_post(struct spi_controller *ctlr, /* Capture the resolution of the timestamp */ xfer->ptp_sts_word_post = progress; - xfer->timestamped = true; + xfer->timestamped = 1; } EXPORT_SYMBOL_GPL(spi_take_timestamp_post); diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 988aabc31871..4fa26b9a3572 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -1022,6 +1022,9 @@ struct spi_transfer { void *rx_buf; unsigned len; +#define SPI_TRANS_FAIL_NO_START BIT(0) + u16 error; + dma_addr_t tx_dma; dma_addr_t rx_dma; struct sg_table tx_sg; @@ -1032,6 +1035,7 @@ struct spi_transfer { unsigned cs_change:1; unsigned tx_nbits:3; unsigned rx_nbits:3; + unsigned timestamped:1; #define SPI_NBITS_SINGLE 0x01 /* 1bit transfer */ #define SPI_NBITS_DUAL 0x02 /* 2bits transfer */ #define SPI_NBITS_QUAD 0x04 /* 4bits transfer */ @@ -1048,12 +1052,7 @@ struct spi_transfer { struct ptp_system_timestamp *ptp_sts; - bool timestamped; - struct list_head transfer_list; - -#define SPI_TRANS_FAIL_NO_START BIT(0) - u16 error; }; /**