From patchwork Tue Oct 6 00:05:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Simmons X-Patchwork-Id: 11817891 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3E8F313B2 for ; Tue, 6 Oct 2020 00:06:42 +0000 (UTC) Received: from pdx1-mailman02.dreamhost.com (pdx1-mailman02.dreamhost.com [64.90.62.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B3757206F4 for ; Tue, 6 Oct 2020 00:06:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B3757206F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lustre-devel-bounces@lists.lustre.org Received: from pdx1-mailman02.dreamhost.com (localhost [IPv6:::1]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id BE1C321F7C8; Mon, 5 Oct 2020 17:06:36 -0700 (PDT) X-Original-To: lustre-devel@lists.lustre.org Delivered-To: lustre-devel-lustre.org@pdx1-mailman02.dreamhost.com Received: from smtp4.ccs.ornl.gov (smtp4.ccs.ornl.gov [160.91.203.40]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id E0B6221F494 for ; Mon, 5 Oct 2020 17:06:27 -0700 (PDT) Received: from star.ccs.ornl.gov (star.ccs.ornl.gov [160.91.202.134]) by smtp4.ccs.ornl.gov (Postfix) with ESMTP id 0320310087CB; Mon, 5 Oct 2020 20:06:25 -0400 (EDT) Received: by star.ccs.ornl.gov (Postfix, from userid 2004) id EA98A2F0E5; Mon, 5 Oct 2020 20:06:24 -0400 (EDT) From: James Simmons To: Andreas Dilger , Oleg Drokin , NeilBrown Date: Mon, 5 Oct 2020 20:05:42 -0400 Message-Id: <1601942781-24950-4-git-send-email-jsimmons@infradead.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1601942781-24950-1-git-send-email-jsimmons@infradead.org> References: <1601942781-24950-1-git-send-email-jsimmons@infradead.org> Subject: [lustre-devel] [PATCH 03/42] lustre: sec: use memchr_inv() to check if page is zero. X-BeenThere: lustre-devel@lists.lustre.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "For discussing Lustre software development." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lustre Development List MIME-Version: 1.0 Errors-To: lustre-devel-bounces@lists.lustre.org Sender: "lustre-devel" From: Mr NeilBrown memchr_inv() is the preferred way to check if a memory region is all zeros. It is likely fast that memcmp() is it doesn't need to read the ZERO_PAGE into cache, or into the CPU. It was introduced in Linux 3.2. WC-bug-id: https://jira.whamcloud.com/browse/LU-12275 Lustre-commit: afee2380c105c ("LU-12275 sec: use memchr_inv() to check if page is zero.") Signed-off-by: Mr NeilBrown Reviewed-on: https://review.whamcloud.com/39459 Reviewed-by: Andreas Dilger Reviewed-by: James Simmons Reviewed-by: Sebastien Buisson Signed-off-by: James Simmons --- fs/lustre/osc/osc_request.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/fs/lustre/osc/osc_request.c b/fs/lustre/osc/osc_request.c index 1e56ca3..fbb8453 100644 --- a/fs/lustre/osc/osc_request.c +++ b/fs/lustre/osc/osc_request.c @@ -2077,9 +2077,8 @@ static int osc_brw_fini_request(struct ptlrpc_request *req, int rc) struct brw_page *pg = aa->aa_ppga[idx]; /* do not decrypt if page is all 0s */ - if (memcmp(page_address(pg->pg), - page_address(ZERO_PAGE(0)), - PAGE_SIZE) == 0) { + if (memchr_inv(page_address(pg->pg), 0, + PAGE_SIZE) == NULL) { /* if page is empty forward info to upper layers * (ll_io_zero_page) by clearing PagePrivate2 */