From patchwork Thu Jan 21 04:16:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 12034419 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 F0DF4C433DB for ; Thu, 21 Jan 2021 04:18:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B1C222343E for ; Thu, 21 Jan 2021 04:18:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B1C222343E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CAD4F6B0005; Wed, 20 Jan 2021 23:18:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C5D686B0008; Wed, 20 Jan 2021 23:18:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B72596B000A; Wed, 20 Jan 2021 23:18:47 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0157.hostedemail.com [216.40.44.157]) by kanga.kvack.org (Postfix) with ESMTP id A11936B0005 for ; Wed, 20 Jan 2021 23:18:47 -0500 (EST) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 65630363E for ; Thu, 21 Jan 2021 04:18:47 +0000 (UTC) X-FDA: 77728476294.23.field81_540695327560 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin23.hostedemail.com (Postfix) with ESMTP id 3FA8337608 for ; Thu, 21 Jan 2021 04:18:47 +0000 (UTC) X-HE-Tag: field81_540695327560 X-Filterd-Recvd-Size: 3310 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf26.hostedemail.com (Postfix) with ESMTP for ; Thu, 21 Jan 2021 04:18:46 +0000 (UTC) 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 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);