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 7DEA2C433DB for ; Thu, 21 Jan 2021 04:22:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 439372368A for ; Thu, 21 Jan 2021 04:22:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728685AbhAUEWI (ORCPT ); Wed, 20 Jan 2021 23:22:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726829AbhAUETc (ORCPT ); Wed, 20 Jan 2021 23:19:32 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B0F51C061575 for ; Wed, 20 Jan 2021 20:18:46 -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=CeaRo8c6b/tUy7+5q7QCW6FJs2iUrrBOGyex33Gpwzg=; b=aX9axA7Wt9qmMjkSbwq775kQhn Sq/B3Kd7H9NLH4PealQQOnu2LIV8HaVcSn+6BvjhQa9PpB0NMUzcxpUvLQbEHbq4l+m2t0Sp/7JYs YRO0AdYJj241TrwIpZjK7y4xllvQoA6i9HjFNNe9mm5eXClm/2zAvNdYxal3R2CEPstrM8iyOKw7L Zr21MSbEHEBscAjMBT3JZXLWt+Jr34xSOXrZsMyYBkd06RbggALPumbVZzzVaWwtr8D2f6BtzK/Be Sx7e6SrfVEjlWTh1GenyvcQhnOrpoWcvRitr6xEjq5vkYwITk0cOhKAgvaqWGKj9alLD2jxxqgaW0 /zGrTqkw==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1l2RPK-00GbBT-PW; Thu, 21 Jan 2021 04:17:25 +0000 From: "Matthew Wilcox (Oracle)" To: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Cc: "Matthew Wilcox (Oracle)" , hch@lst.de, kent.overstreet@gmail.com Subject: [PATCH v4 02/18] mm/filemap: Remove dynamically allocated array from filemap_read Date: Thu, 21 Jan 2021 04:16:00 +0000 Message-Id: <20210121041616.3955703-3-willy@infradead.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210121041616.3955703-1-willy@infradead.org> References: <20210121041616.3955703-1-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) --- mm/filemap.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 934e04f1760ef..5dec04c8e16b0 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2421,8 +2421,8 @@ 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; @@ -2433,14 +2433,6 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, return 0; 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(); @@ -2525,9 +2517,6 @@ 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