From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758737AbaIOU7W (ORCPT ); Mon, 15 Sep 2014 16:59:22 -0400 Received: from mail-ig0-f171.google.com ([209.85.213.171]:56474 "EHLO mail-ig0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755734AbaIOU7T (ORCPT ); Mon, 15 Sep 2014 16:59:19 -0400 From: Dan Streetman To: Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Nitin Gupta , Seth Jennings , Andrew Morton , Dan Streetman Subject: [PATCH] zsmalloc: simplify init_zspage free obj linking Date: Mon, 15 Sep 2014 16:58:50 -0400 Message-Id: <1410814730-5740-1-git-send-email-ddstreet@ieee.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <20140914232427.GD2160@bbox> References: <20140914232427.GD2160@bbox> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Change zsmalloc init_zspage() logic to iterate through each object on each of its pages, checking the offset to verify the object is on the current page before linking it into the zspage. The current zsmalloc init_zspage free object linking code has logic that relies on there only being one page per zspage when PAGE_SIZE is a multiple of class->size. It calculates the number of objects for the current page, and iterates through all of them plus one, to account for the assumed partial object at the end of the page. While this currently works, the logic can be simplified to just link the object at each successive offset until the offset is larger than PAGE_SIZE, which does not rely on PAGE_SIZE being a multiple of class->size. Signed-off-by: Dan Streetman Cc: Minchan Kim --- mm/zsmalloc.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index c4a9157..03aa72f 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -628,7 +628,7 @@ static void init_zspage(struct page *first_page, struct size_class *class) while (page) { struct page *next_page; struct link_free *link; - unsigned int i, objs_on_page; + unsigned int i = 1; /* * page->index stores offset of first object starting @@ -641,14 +641,10 @@ static void init_zspage(struct page *first_page, struct size_class *class) link = (struct link_free *)kmap_atomic(page) + off / sizeof(*link); - objs_on_page = (PAGE_SIZE - off) / class->size; - for (i = 1; i <= objs_on_page; i++) { - off += class->size; - if (off < PAGE_SIZE) { - link->next = obj_location_to_handle(page, i); - link += class->size / sizeof(*link); - } + while ((off += class->size) < PAGE_SIZE) { + link->next = obj_location_to_handle(page, i++); + link += class->size / sizeof(*link); } /* @@ -660,7 +656,7 @@ static void init_zspage(struct page *first_page, struct size_class *class) link->next = obj_location_to_handle(next_page, 0); kunmap_atomic(link); page = next_page; - off = (off + class->size) % PAGE_SIZE; + off %= PAGE_SIZE; } } -- 1.8.3.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f178.google.com (mail-ie0-f178.google.com [209.85.223.178]) by kanga.kvack.org (Postfix) with ESMTP id 984036B0080 for ; Mon, 15 Sep 2014 16:59:19 -0400 (EDT) Received: by mail-ie0-f178.google.com with SMTP id tp5so5415954ieb.37 for ; Mon, 15 Sep 2014 13:59:19 -0700 (PDT) Received: from mail-ie0-x232.google.com (mail-ie0-x232.google.com [2607:f8b0:4001:c03::232]) by mx.google.com with ESMTPS id bg2si4582icb.58.2014.09.15.13.59.18 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 15 Sep 2014 13:59:19 -0700 (PDT) Received: by mail-ie0-f178.google.com with SMTP id tp5so5181911ieb.23 for ; Mon, 15 Sep 2014 13:59:18 -0700 (PDT) From: Dan Streetman Subject: [PATCH] zsmalloc: simplify init_zspage free obj linking Date: Mon, 15 Sep 2014 16:58:50 -0400 Message-Id: <1410814730-5740-1-git-send-email-ddstreet@ieee.org> In-Reply-To: <20140914232427.GD2160@bbox> References: <20140914232427.GD2160@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Nitin Gupta , Seth Jennings , Andrew Morton , Dan Streetman Change zsmalloc init_zspage() logic to iterate through each object on each of its pages, checking the offset to verify the object is on the current page before linking it into the zspage. The current zsmalloc init_zspage free object linking code has logic that relies on there only being one page per zspage when PAGE_SIZE is a multiple of class->size. It calculates the number of objects for the current page, and iterates through all of them plus one, to account for the assumed partial object at the end of the page. While this currently works, the logic can be simplified to just link the object at each successive offset until the offset is larger than PAGE_SIZE, which does not rely on PAGE_SIZE being a multiple of class->size. Signed-off-by: Dan Streetman Cc: Minchan Kim --- mm/zsmalloc.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index c4a9157..03aa72f 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -628,7 +628,7 @@ static void init_zspage(struct page *first_page, struct size_class *class) while (page) { struct page *next_page; struct link_free *link; - unsigned int i, objs_on_page; + unsigned int i = 1; /* * page->index stores offset of first object starting @@ -641,14 +641,10 @@ static void init_zspage(struct page *first_page, struct size_class *class) link = (struct link_free *)kmap_atomic(page) + off / sizeof(*link); - objs_on_page = (PAGE_SIZE - off) / class->size; - for (i = 1; i <= objs_on_page; i++) { - off += class->size; - if (off < PAGE_SIZE) { - link->next = obj_location_to_handle(page, i); - link += class->size / sizeof(*link); - } + while ((off += class->size) < PAGE_SIZE) { + link->next = obj_location_to_handle(page, i++); + link += class->size / sizeof(*link); } /* @@ -660,7 +656,7 @@ static void init_zspage(struct page *first_page, struct size_class *class) link->next = obj_location_to_handle(next_page, 0); kunmap_atomic(link); page = next_page; - off = (off + class->size) % PAGE_SIZE; + off %= PAGE_SIZE; } } -- 1.8.3.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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