From patchwork Mon Dec 13 14:43:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Laight X-Patchwork-Id: 12674063 X-Patchwork-Delegate: kuba@kernel.org 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 C0FF0C433F5 for ; Mon, 13 Dec 2021 14:43:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239706AbhLMOnw (ORCPT ); Mon, 13 Dec 2021 09:43:52 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.85.151]:23625 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239684AbhLMOnw (ORCPT ); Mon, 13 Dec 2021 09:43:52 -0500 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-54-zFq3ZrzlNPa02HnbPWuBlQ-1; Mon, 13 Dec 2021 14:43:50 +0000 X-MC-Unique: zFq3ZrzlNPa02HnbPWuBlQ-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.26; Mon, 13 Dec 2021 14:43:48 +0000 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.026; Mon, 13 Dec 2021 14:43:48 +0000 From: David Laight To: David Laight , 'Noah Goldstein' , Eric Dumazet CC: "tglx@linutronix.de" , "mingo@redhat.com" , Borislav Petkov , "dave.hansen@linux.intel.com" , X86 ML , "hpa@zytor.com" , "peterz@infradead.org" , "alexanderduyck@fb.com" , open list , netdev Subject: [PATCH] x86/lib: Remove the special case for odd-aligned buffers in csum_partial.c Thread-Topic: [PATCH] x86/lib: Remove the special case for odd-aligned buffers in csum_partial.c Thread-Index: AdfwL8CqMU0zbyVyQYmiKOZRxmZfsg== Date: Mon, 13 Dec 2021 14:43:48 +0000 Message-ID: <45d12aa0c95049a392d52ff239d42d83@AcuMS.aculab.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org There is no need to special case the very unusual odd-aligned buffers. They are no worse than 4n+2 aligned buffers. Signed-off-by: David Laight Reviewed-by: Eric Dumazet --- On an i7-7700 misaligned buffers add 2 or 3 clocks (in 115) to a 512 byte checksum. That is just measuring the main loop with an lfence prior to rdpmc to read PERF_COUNT_HW_CPU_CYCLES. arch/x86/lib/csum-partial_64.c | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-) diff --git a/arch/x86/lib/csum-partial_64.c b/arch/x86/lib/csum-partial_64.c index 40b527ba1da1..abf819dd8525 100644 --- a/arch/x86/lib/csum-partial_64.c +++ b/arch/x86/lib/csum-partial_64.c @@ -35,17 +35,7 @@ static inline unsigned short from32to16(unsigned a) __wsum csum_partial(const void *buff, int len, __wsum sum) { u64 temp64 = (__force u64)sum; - unsigned odd, result; - - odd = 1 & (unsigned long) buff; - if (unlikely(odd)) { - if (unlikely(len == 0)) - return sum; - temp64 = ror32((__force u32)sum, 8); - temp64 += (*(unsigned char *)buff << 8); - len--; - buff++; - } + unsigned result; while (unlikely(len >= 64)) { asm("addq 0*8(%[src]),%[res]\n\t" @@ -130,10 +120,6 @@ __wsum csum_partial(const void *buff, int len, __wsum sum) #endif } result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff); - if (unlikely(odd)) { - result = from32to16(result); - result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); - } return (__force __wsum)result; } EXPORT_SYMBOL(csum_partial);