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[2620:137:e000::1:20]) by mx.google.com with ESMTP id ji10-20020a170907980a00b007123952b00dsi329786ejc.100.2022.10.28.18.18.55; Fri, 28 Oct 2022 18:19:18 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=g02qEJsW; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229718AbiJ2AwE (ORCPT + 99 others); Fri, 28 Oct 2022 20:52:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229552AbiJ2AwD (ORCPT ); Fri, 28 Oct 2022 20:52:03 -0400 Received: from mail-qt1-x836.google.com (mail-qt1-x836.google.com [IPv6:2607:f8b0:4864:20::836]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C39B2D0185; Fri, 28 Oct 2022 17:52:00 -0700 (PDT) Received: by mail-qt1-x836.google.com with SMTP id ay12so3878314qtb.12; Fri, 28 Oct 2022 17:52:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=v5RiV+Px8WS2ShlcDdYeA2/trOi8fP9YvmZ25k/CKak=; b=g02qEJsW4N4aEjtM2laW+nJCEU2K+n+vd3qaVpXcdBqYfi35cSrb3J3RhQhtftmcpj 7Sw42lNEJuQJl4x0yoJ3nc+1xtoXk9y2NWCHBbEPGN1jUPz82/lddDcLogq7H/pYt6Wd 7jR21fg86kFw6FI99VHNURki10cISy3GEFpKpdAZUa+7le46Nz6rRd/d0SviYF7hthIi 6ryQBP76Vsa2qA+AVxLu4pxRbhA+sXdDp3CLlCB3M9FsgEYO567PpOyr2TQRho8cesCu RwfDRjeABE64l5SRnc6xmdEJw62+9Crx31nLjWi+PZSnoMU6bq95n3O/xhrk8mn3giY8 ljzQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=v5RiV+Px8WS2ShlcDdYeA2/trOi8fP9YvmZ25k/CKak=; b=VFxa9D0TF4M1N/jWArU1nOxlr27Tt3fTildtXBVmlxN65krywv9oSGcBsjKPIG3Jue lYTpW5gSTF3m1tgy9ssKV4RsVCuH5w79DV+qlCHsSDwpZeCJH4YEnuDQo131CxPKakUc px6PH5UyUOIq/7AoF/g4x6p+jzDSasXKk9HOEuOxdU2RIywdso6oyZe+FLeu1W11tKgV RRMb/TfvENxAhCKaW2vluLRUIMvIINvz9Yafw9bNqWlNQ3IrqEilYPP0aZbPubpkqaOi tZcvQoE3QVjaTlCgpfJTSq9w6BfSwwO47CBmIR7HV/HmpOzR/R4uB1kxJ7+mTgutKZTy ymIA== X-Gm-Message-State: ACrzQf1oVGvDGTKAd07WEE98jLK6coak6Zujoizlyr01OrLScn0YphBD qPoTWicpuaiZ2whK+iV8TQ== X-Received: by 2002:a05:622a:198e:b0:39c:e98c:d3e1 with SMTP id u14-20020a05622a198e00b0039ce98cd3e1mr1934014qtc.378.1667004719888; Fri, 28 Oct 2022 17:51:59 -0700 (PDT) Received: from bytedance.attlocal.net ([130.44.212.155]) by smtp.gmail.com with ESMTPSA id bs6-20020a05620a470600b006b61b2cb1d2sm133935qkb.46.2022.10.28.17.51.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Oct 2022 17:51:59 -0700 (PDT) From: Peilin Ye To: Alexander Viro Cc: Peilin Ye , Cong Wang , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Peilin Ye Subject: [PATCH v1] coredump: Use vmsplice_to_pipe() for pipes in dump_emit_page() Date: Fri, 28 Oct 2022 17:51:47 -0700 Message-Id: <20221029005147.2553-1-yepeilin.cs@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1747982859483774529?= X-GMAIL-MSGID: =?utf-8?q?1747982859483774529?= From: Peilin Ye Currently, there is a copy for each page when dumping VMAs to pipe handlers using dump_emit_page(). For example: fs/binfmt_elf.c:elf_core_dump() fs/coredump.c:dump_user_range() :dump_emit_page() fs/read_write.c:__kernel_write_iter() fs/pipe.c:pipe_write() lib/iov_iter.c:copy_page_from_iter() Use vmsplice_to_pipe() instead of __kernel_write_iter() to avoid this copy for pipe handlers. Tested by dumping a 40-GByte core into a simple handler that splice()s from stdin to disk in a loop, PIPE_DEF_BUFFERS (16) pages at a time. Before After Improved by Time to Completion 52.04 seconds 46.30 seconds 11.03% CPU Usage 89.43% 84.90% 5.07% Suggested-by: Cong Wang Signed-off-by: Peilin Ye --- fs/coredump.c | 7 ++++++- fs/splice.c | 4 ++-- include/linux/splice.h | 2 ++ 3 files changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 7bad7785e8e6..a6ef406dee43 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -42,6 +42,7 @@ #include #include #include +#include #include #include @@ -854,7 +855,11 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page) return 0; pos = file->f_pos; iov_iter_bvec(&iter, WRITE, &bvec, 1, PAGE_SIZE); - n = __kernel_write_iter(cprm->file, &iter, &pos); + + n = vmsplice_to_pipe(file, &iter, 0); + if (n == -EBADF) + n = __kernel_write_iter(cprm->file, &iter, &pos); + if (n != PAGE_SIZE) return 0; file->f_pos = pos; diff --git a/fs/splice.c b/fs/splice.c index 0878b852b355..2051700cda79 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -1234,8 +1234,8 @@ static long vmsplice_to_user(struct file *file, struct iov_iter *iter, * as splice-from-memory, where the regular splice is splice-from-file (or * to file). In both cases the output is a pipe, naturally. */ -static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter, - unsigned int flags) +long vmsplice_to_pipe(struct file *file, struct iov_iter *iter, + unsigned int flags) { struct pipe_inode_info *pipe; long ret = 0; diff --git a/include/linux/splice.h b/include/linux/splice.h index a55179fd60fc..0cd955cf5ee2 100644 --- a/include/linux/splice.h +++ b/include/linux/splice.h @@ -81,6 +81,8 @@ extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *, extern long do_splice(struct file *in, loff_t *off_in, struct file *out, loff_t *off_out, size_t len, unsigned int flags); +extern long vmsplice_to_pipe(struct file *file, struct iov_iter *iter, + unsigned int flags); extern long do_tee(struct file *in, struct file *out, size_t len, unsigned int flags);