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=-9.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 4C1F7C433E1 for ; Thu, 13 Aug 2020 11:19:40 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0102320715 for ; Thu, 13 Aug 2020 11:19:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Bs17dOkN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0102320715 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 736A66B000A; Thu, 13 Aug 2020 07:19:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6BE436B000C; Thu, 13 Aug 2020 07:19:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 537586B000D; Thu, 13 Aug 2020 07:19:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0102.hostedemail.com [216.40.44.102]) by kanga.kvack.org (Postfix) with ESMTP id 393366B000A for ; Thu, 13 Aug 2020 07:19:39 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 565035DD7 for ; Thu, 13 Aug 2020 11:19:38 +0000 (UTC) X-FDA: 77145300036.29.bear15_4406b8d26ff3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin29.hostedemail.com (Postfix) with ESMTP id 6A15C18086CD9 for ; Thu, 13 Aug 2020 11:19:37 +0000 (UTC) X-HE-Tag: bear15_4406b8d26ff3 X-Filterd-Recvd-Size: 2959 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Thu, 13 Aug 2020 11:19:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=tZ4dSaPwhhsxFzT6mKk9i9S+yw6lUP7cNS/nYMzBjsg=; b=Bs17dOkNYuKL6MX/i8oURZEgqN 6ihWx3b+0VUUs44qNZ0kjNXOps7S7KIzwoA3WAsMfjZ9UwP4lzGFBEeb/OLPANETS79IBRtwJpudC Ae1I6Y4I72qcf7PeI5SLXhUir3AFe23SJMxdhgEFw6TImX2pwrpsE6vsfycUZPg9h+28Xnpr1HI7k gGPRUjYHA9gt/SaTBHnC11KrFr1sq3nthFK6d64AypGWNmdtZuhoJ64VKn8355lhZPh7fkrYkD1DI g0AN6HFJvJgDe93wrMhrQ5aZdsdlm3SjORHQpeeh0qYiwedKasd/UwoYmYqMoCpz2ouVqeOEeDg0P F/jhuwrw==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1k6BGW-0001EG-IK; Thu, 13 Aug 2020 11:19:24 +0000 Date: Thu, 13 Aug 2020 12:19:24 +0100 From: Matthew Wilcox To: Zhaoyang Huang Cc: Roman Gushchin , Andrew Morton , Zhaoyang Huang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] mm : using bdi->ra_pages instead of ra->ra_pages within readahead Message-ID: <20200813111924.GE17456@casper.infradead.org> References: <1597306282-29927-1-git-send-email-zhaoyang.huang@unisoc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1597306282-29927-1-git-send-email-zhaoyang.huang@unisoc.com> X-Rspamd-Queue-Id: 6A15C18086CD9 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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: On Thu, Aug 13, 2020 at 04:11:22PM +0800, Zhaoyang Huang wrote: > file->f_ra->ra_pages will remain the initialized value since it opend, which may > be NOT equal to bdi->ra_pages as the latter one is updated somehow(etc, > echo xxx > /sys/block/dm/queue/read_ahead_kb).So having readahead use > bdi->ra_pages. But now it ignores the work done by shrink_readahead_size_eio() and fadvise(POSIX_FADV_SEQUENTIAL). And you missed the use of ra_size on the previous line, miscalculating ra->start. > Signed-off-by: Zhaoyang Huang > --- > mm/filemap.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index d78f577..259dcfd 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2499,8 +2499,8 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) > */ > fpin = maybe_unlock_mmap_for_io(vmf, fpin); > ra->start = max_t(long, 0, offset - ra->ra_pages / 2); > - ra->size = ra->ra_pages; > - ra->async_size = ra->ra_pages / 4; > + ra->size = inode_to_bdi(mapping->host)->ra_pages; > + ra->async_size = ra->size / 4; > ra_submit(ra, mapping, file); > return fpin; > } > -- > 1.9.1 > >