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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F806C67871 for ; Mon, 24 Oct 2022 20:31:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234314AbiJXUbJ (ORCPT ); Mon, 24 Oct 2022 16:31:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234307AbiJXUaj (ORCPT ); Mon, 24 Oct 2022 16:30:39 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 909A8106A6E for ; Mon, 24 Oct 2022 11:42:51 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id D8205CE13C1 for ; Mon, 24 Oct 2022 16:15:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9BAD9C433C1; Mon, 24 Oct 2022 16:15:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666628118; bh=fbb9TnyA4/QkQJN70OgJtJjtXVcbpv/1y+hOOr3/wPc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dFybjEOCLlMv8grYfY0I4MiqF+Ww8ZGQCeLIqhmF8tony0k7HuNvErIitm1JgIBbM xGLMfLfjRLMYzjZJeZDOnHYrwoNh/GGB5tTW3yP/nnGPlOejt4fBaPAq40LUl3CArB qMS8WTcP3IUBD6aoV4lxwRLFu5xaoKXbk9iCu5uIevLy7Ua9a/a5VB1b5ZmY4kXPSZ Ut/FVUKndGeEFHwE0MDt2fKlaFJV2MhrdZZy63Xw2hl5SWy7+guy1NyMcpK4qgi9gf FMjbCdzl4VRck7aj0nw7vTeMG6PPDsXHfAK5wcl95ScxdowLjS65D6TtMkrju/0JEY jMtNnq48xwFlg== Date: Mon, 24 Oct 2022 19:15:02 +0300 From: Mike Rapoport To: Yajun Deng Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] memblock: remove repeat round Message-ID: References: <20221019120337.2098298-1-yajun.deng@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221019120337.2098298-1-yajun.deng@linux.dev> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wed, Oct 19, 2022 at 08:03:37PM +0800, Yajun Deng wrote: > Subject: memblock: remove repeat round Please make the patch subject more detailed. Say membloc: don't run loop in memblock_add_range() twice > There is no need round twice in memblock_add_range(). > > We can call memblock_double_array() to extand the size if type->cnt no ^ extend > less than type->max before memblock_insert_region(), otherwise we can s/no less than/greater or equal to/ > insert the new region directly. > > Signed-off-by: Yajun Deng > --- > mm/memblock.c | 54 +++++++++++++++------------------------------------ > 1 file changed, 16 insertions(+), 38 deletions(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 511d4783dcf1..1679244b4a1a 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -578,7 +578,6 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, > phys_addr_t base, phys_addr_t size, > int nid, enum memblock_flags flags) > { > - bool insert = false; > phys_addr_t obase = base; > phys_addr_t end = base + memblock_cap_size(base, &size); > int idx, nr_new; > @@ -598,22 +597,6 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, > return 0; > } > > - /* > - * The worst case is when new range overlaps all existing regions, > - * then we'll need type->cnt + 1 empty regions in @type. So if > - * type->cnt * 2 + 1 is less than type->max, we know > - * that there is enough empty regions in @type, and we can insert > - * regions directly. > - */ > - if (type->cnt * 2 + 1 < type->max) > - insert = true; > - > -repeat: > - /* > - * The following is executed twice. Once with %false @insert and > - * then with %true. The first counts the number of regions needed > - * to accommodate the new area. The second actually inserts them. > - */ > base = obase; > nr_new = 0; I believe nr_new variable is no longer needed, is it? > @@ -635,10 +618,14 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, > #endif > WARN_ON(flags != rgn->flags); > nr_new++; > - if (insert) > - memblock_insert_region(type, idx++, base, > - rbase - base, nid, > - flags); > + > + if ((type->cnt >= type->max) && > + (memblock_double_array(type, obase, size) < 0)) if ((type->cnt >= type->max) && memblock_double_array(type, obase, size)) would be just fine. I'd appreciate a comment above the if statement explaining when the allocation is required. > + return -ENOMEM; > + > + memblock_insert_region(type, idx++, base, > + rbase - base, nid, > + flags); > } > /* area below @rend is dealt with, forget about it */ > base = min(rend, end); > @@ -647,28 +634,19 @@ static int __init_memblock memblock_add_range(struct memblock_type *type, > /* insert the remaining portion */ > if (base < end) { > nr_new++; > - if (insert) > - memblock_insert_region(type, idx, base, end - base, > - nid, flags); > + if ((type->cnt >= type->max) && > + (memblock_double_array(type, obase, size) < 0)) > + return -ENOMEM; > + > + memblock_insert_region(type, idx, base, end - base, > + nid, flags); > } > > if (!nr_new) > return 0; > > - /* > - * If this was the first round, resize array and repeat for actual > - * insertions; otherwise, merge and return. > - */ > - if (!insert) { > - while (type->cnt + nr_new > type->max) > - if (memblock_double_array(type, obase, size) < 0) > - return -ENOMEM; > - insert = true; > - goto repeat; > - } else { > - memblock_merge_regions(type); > - return 0; > - } > + memblock_merge_regions(type); A blank line here would be nice. > + return 0; > } > > /** > -- > 2.25.1 > > -- Sincerely yours, Mike.