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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 207D3C433E6 for ; Fri, 22 Jan 2021 16:05:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E39D422EBE for ; Fri, 22 Jan 2021 16:05:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729363AbhAVQEl (ORCPT ); Fri, 22 Jan 2021 11:04:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729366AbhAVQEQ (ORCPT ); Fri, 22 Jan 2021 11:04:16 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 653DDC0613D6; Fri, 22 Jan 2021 08:03:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=bJrHcc3TRuo3zacTOm7nFFwlB8n6a0vSf1BsFy5yvWQ=; b=UKPS+BewMN+ObHxdDV7pNY8in4 d9ph4PhrCy1FYoao5Lt9YvjBfIYfrHSEGPWJj5E9L9MqjqtRwEjM/ExkPiDCNm2Iz3kEYRU4oMpTF Bh206af6zhRXC8+wx7nYXN6SP3Ve3EiviJFg1ykq+SVM+jtVamePjfj5weYJDZYOgpXTa2fRcI+dB oU0g91XHwKHqpQ2mDQztKYZ1B3Jjh29uPgGR8Id45+TdAm/32EKm9715xAh/u3/DjrrzaAwFmJsbE +kIe6kkJZ6JqiFpGYQJlh0s4tFyqSWDzqI+mPBiplMywYnHsIIDzUZuJSfpSdVSMFhZ8RxrPbcUr9 9ZJlmsRg==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1l2ytq-000wAw-An; Fri, 22 Jan 2021 16:03:09 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Hellwig , Miaohe Lin Subject: [PATCH v5 02/18] mm/filemap: Remove dynamically allocated array from filemap_read Date: Fri, 22 Jan 2021 16:01:24 +0000 Message-Id: <20210122160140.223228-3-willy@infradead.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210122160140.223228-1-willy@infradead.org> References: <20210122160140.223228-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Increasing the batch size runs into diminishing returns. It's probably better to make, eg, three calls to filemap_get_pages() than it is to call into kmalloc(). Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Reviewed-by: Miaohe Lin --- mm/filemap.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index afc0f674f2242..a5c4f7ddfc40c 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2444,8 +2444,8 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, struct file_ra_state *ra = &filp->f_ra; struct address_space *mapping = filp->f_mapping; struct inode *inode = mapping->host; - struct page *pages_onstack[PAGEVEC_SIZE], **pages = NULL; - unsigned int nr_pages = min_t(unsigned int, 512, + struct page *pages[PAGEVEC_SIZE]; + unsigned int nr_pages = min_t(unsigned int, PAGEVEC_SIZE, ((iocb->ki_pos + iter->count + PAGE_SIZE - 1) >> PAGE_SHIFT) - (iocb->ki_pos >> PAGE_SHIFT)); int i, pg_nr, error = 0; @@ -2459,14 +2459,6 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, iov_iter_truncate(iter, inode->i_sb->s_maxbytes); - if (nr_pages > ARRAY_SIZE(pages_onstack)) - pages = kmalloc_array(nr_pages, sizeof(void *), GFP_KERNEL); - - if (!pages) { - pages = pages_onstack; - nr_pages = min_t(unsigned int, nr_pages, ARRAY_SIZE(pages_onstack)); - } - do { cond_resched(); @@ -2551,9 +2543,6 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, file_accessed(filp); - if (pages != pages_onstack) - kfree(pages); - return written ? written : error; } EXPORT_SYMBOL_GPL(generic_file_buffered_read); -- 2.29.2