From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751348AbbCTHB4 (ORCPT ); Fri, 20 Mar 2015 03:01:56 -0400 Received: from mailout2.samsung.com ([203.254.224.25]:63600 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750756AbbCTHBx (ORCPT ); Fri, 20 Mar 2015 03:01:53 -0400 X-AuditID: cbfee6a2-f79656d00000586c-27-550bc5df3059 Date: Fri, 20 Mar 2015 07:01:51 +0000 (GMT) From: Yinghao Xie Subject: Re: Re: mm/zsmalloc.c: count in handle's size when calculating pages_per_zspage To: Minchan Kim Cc: Andrew Morton , Nitin Gupta , mm , lkml Reply-to: yinghao.xie@samsung.com MIME-version: 1.0 X-MTR: 20150320065142737@yinghao.xie Msgkey: 20150320065142737@yinghao.xie X-EPLocale: zh_CN.utf-8 X-Priority: 3 X-EPWebmail-Msg-Type: personal X-EPWebmail-Reply-Demand: 0 X-EPApproval-Locale: X-EPHeader: ML X-MLAttribute: X-RootMTR: 20150320065142737@yinghao.xie X-ParentMTR: X-ArchiveUser: X-CPGSPASS: N X-ConfirmMail: N,general Content-type: text/plain; charset=utf-8 MIME-version: 1.0 Message-id: <2096325123.41201426834909043.JavaMail.weblogic@epmlwas06d> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrHIsWRmVeSWpSXmKPExsVy+t/tPt37R7lDDR7857K4vGsOmwOjx+dN cgGMUVw2Kak5mWWpRfp2CVwZ7/5+Yy1Yp1Zxq+kbYwPjGtUuRk4OIQE1iY4Vr5lAbAkBE4m3 s8+yQdhiEhfurQeyuYBq5jBKtH+ZApZgEVCVeDirgbGLkYODTUBHYtsxHZCwsECExI0JF1lA bBGQmcebwHqZBWYxSnxY/podYpmiRMPr1WBFvAKCEidnPmGBWKYi0Xqqlx0iriqx+tljZoi4 uMSniVehDuKVmNH+FKpeTmLa1zVQNdIS52dtYIQ5evF3mF5+iWO3d0A9JiAx9cxBqBpNidsH v0DN5JNYs/AtC0z9rlPLmWF23d8yF6pXQmJryxNWEJsZ6P4p3Q/ZQX5nBpqzfpc+qlc4gGx3 iY/33SYwys5CkpmFpHkWQjOykgWMLKsYRVMLkguKk9IrjPSKE3OLS/PS9ZLzczcxgmP52aId jP/OWx9iFOBgVOLhPVDKHSrEmlhWXJl7iFGCg1lJhNdjE1CINyWxsiq1KD++qDQntfgQozQH i5I47/9zuSFCAumJJanZqakFqUUwWSYOTqkGxsU/yxZeLH7rWxN4ah6v8eQA5iwOu0+Jb0x2 Cjz1Kny4q0Hhg5fWNqmwvIWXDfXO3/q65Y2jRUtFWeKm7C5/yU07mk57PP2Ra6/rJlenqpOz hidgUvPS6zZ9HQU90x5ms23ozVQWOl9z/7hwrfqGtqYlvaqpl+5ZVaw/OFvqbleTWMTyCbfy lViKMxINtZiLihMBmD6aNeECAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id t2K721BZ023349 > > From 159d74b5a8f3d0f07e18ddad74b7025cf17dcc69 Mon Sep 17 00:00:00 > 2001 > > From: Yinghao Xie > > Date: Thu, 19 Mar 2015 19:32:25 +0800 > > Subject: [PATCH] mm/zsmalloc.c: count in handle's size when > > calculating size_class's pages_per_zspage > > > > 1. Fix wastage calculation; > > 2. Indirect handle introduced extra ZS_HANDLE_SIZE size for each > object,it's transparent > > for upper function, but a size_class's total objects will changed: > > take the 43rd class which class_size = 32 + 43 * 16 = 720 as example: > > 4096 * 1 % 720 = 496 > > 4096 * 2 % 720 = 272 > > 4096 * 3 % 720 = 48 > > 4096 * 4 %720 = 544 > > after handle introduced,class_size + ZS_HANDLE_SIZE (4 on 32bit) = 724 > > 4096 * 1 % 724 = 476 > > 4096 * 2 % 724 = 228 > > 4096 * 3 % 724 = 704 > > 4096 * 4 % 724 = 456 > > Clearly, ZS_HANDLE_SIZE should be considered when calculating > > pages_per_zspage; > > Zsmalloc adds ZS_SIZE_HANDLE to size user passed before getting size_class > so we don't need to change size_class to calculate optimal pages for zspage. > I read code agian,and agreed with you,it is my misunderstanding > > > > 3. in get_size_class_index(), min(zs_size_classes - 1, idx) insures a huge > class's > > index <= zs_size_classes - 1, so it's no need to check again; > > Sorry, I don't get it, either. > ditto, my fault,sorry > > > > Signed-off-by: Yinghao Xie > > --- > > mm/zsmalloc.c | 15 ++++++--------- > > 1 file changed, 6 insertions(+), 9 deletions(-) > > > > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 461243e..64c379b > > 100644 > > --- a/mm/zsmalloc.c > > +++ b/mm/zsmalloc.c > > @@ -760,7 +760,8 @@ out: > > * to form a zspage for each size class. This is important > > * to reduce wastage due to unusable space left at end of > > * each zspage which is given as: > > - * wastage = Zp - Zp % size_class > > + * wastage = Zp % (class_size + ZS_HANDLE_SIZE) > > + * usage = Zp - wastage > > * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ... > > * > > * For example, for size class of 3/8 * PAGE_SIZE, we should @@ > > -773,6 +774,9 @@ static int get_pages_per_zspage(int class_size) > > /* zspage order which gives maximum used size per KB */ > > int max_usedpc_order = 1; > > > > + if (class_size > ZS_MAX_ALLOC_SIZE) > > + class_size = ZS_MAX_ALLOC_SIZE; > > + > > for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) { > > int zspage_size; > > int waste, usedpc; > > @@ -1426,11 +1430,6 @@ unsigned long zs_malloc(struct zs_pool *pool, > size_t size) > > /* extra space in chunk to keep the handle */ > > size += ZS_HANDLE_SIZE; > > class = pool->size_class[get_size_class_index(size)]; > > - /* In huge class size, we store the handle into first_page->private */ > > - if (class->huge) { > > - size -= ZS_HANDLE_SIZE; > > - class = pool->size_class[get_size_class_index(size)]; > > - } > > > > spin_lock(&class->lock); > > first_page = find_get_zspage(class); @@ -1856,9 +1855,7 @@ struct > > zs_pool *zs_create_pool(char *name, gfp_t flags) > > struct size_class *class; > > > > size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA; > > - if (size > ZS_MAX_ALLOC_SIZE) > > - size = ZS_MAX_ALLOC_SIZE; > > - pages_per_zspage = get_pages_per_zspage(size); > > + pages_per_zspage = get_pages_per_zspage(size + > ZS_HANDLE_SIZE); > > > > /* > > * size_class is used for normal zsmalloc operation such > > -- > > 1.7.9.5 {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I