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 X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2870C4361B for ; Wed, 9 Dec 2020 14:49:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 892DE23406 for ; Wed, 9 Dec 2020 14:49:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733106AbgLIOt3 (ORCPT ); Wed, 9 Dec 2020 09:49:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:50666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733076AbgLIOt3 (ORCPT ); Wed, 9 Dec 2020 09:49:29 -0500 From: trondmy@kernel.org Authentication-Results: mail.kernel.org; dkim=permerror (bad message/signature format) To: linux-nfs@vger.kernel.org Subject: [PATCH 08/16] SUNRPC: Avoid unnecessary copies in xdr_buf_pages_copy_left/right() Date: Wed, 9 Dec 2020 09:47:53 -0500 Message-Id: <20201209144801.700778-9-trondmy@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201209144801.700778-8-trondmy@kernel.org> References: <20201209144801.700778-1-trondmy@kernel.org> <20201209144801.700778-2-trondmy@kernel.org> <20201209144801.700778-3-trondmy@kernel.org> <20201209144801.700778-4-trondmy@kernel.org> <20201209144801.700778-5-trondmy@kernel.org> <20201209144801.700778-6-trondmy@kernel.org> <20201209144801.700778-7-trondmy@kernel.org> <20201209144801.700778-8-trondmy@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Trond Myklebust Moving data in the XDR page arrays can be expensive, since it can involve touching up to a megabyte of data. Try to avoid doing so for the case where the server returned less data than we preallocated. Signed-off-by: Trond Myklebust --- net/sunrpc/xdr.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 7ca6208e7623..86a48c4cdcfc 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -600,14 +600,20 @@ static void xdr_buf_tail_shift_right(const struct xdr_buf *buf, static void xdr_buf_pages_shift_right(const struct xdr_buf *buf, unsigned int base, unsigned int shift) { + struct xdr_buf subbuf; + if (!shift) return; if (base >= buf->page_len) { xdr_buf_tail_shift_right(buf, base - buf->page_len, shift); return; } - xdr_buf_tail_shift_right(buf, 0, shift); - xdr_buf_pages_copy_right(buf, base, shift); + base += buf->head->iov_len; + if (base >= buf->len) + return; + xdr_buf_subsegment(buf, &subbuf, base, buf->len - base); + xdr_buf_tail_shift_right(&subbuf, 0, shift); + xdr_buf_pages_copy_right(&subbuf, 0, shift); } static void xdr_buf_head_shift_right(const struct xdr_buf *buf, @@ -710,14 +716,16 @@ static void xdr_buf_tail_shift_left(const struct xdr_buf *buf, static void xdr_buf_pages_shift_left(const struct xdr_buf *buf, unsigned int base, unsigned int shift) { + struct xdr_buf subbuf; if (!shift) return; if (base >= buf->page_len) { xdr_buf_tail_shift_left(buf, base - buf->page_len, shift); return; } - xdr_buf_pages_copy_left(buf, base, shift); - xdr_buf_tail_shift_left(buf, 0, shift); + xdr_buf_subsegment(buf, &subbuf, 0, buf->len); + xdr_buf_pages_copy_left(&subbuf, base, shift); + xdr_buf_tail_shift_left(&subbuf, 0, shift); } /** -- 2.29.2