From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 8 Mar 2005 10:22:47 +0000 (GMT) From: Mel Gorman Subject: Re: [PATCH] 2/2 Prezeroing large blocks of pages during allocation Version 4 In-Reply-To: <422D42BF.4060506@jp.fujitsu.com> Message-ID: References: <20050307194021.E6A86E594@skynet.csn.ul.ie> <422D42BF.4060506@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, clameter@sgi.com List-ID: On Tue, 8 Mar 2005, KAMEZAWA Hiroyuki wrote: > Hi, > > Mel Gorman wrote: > > > +#define BITS_PER_ALLOC_TYPE 5 > > #define ALLOC_KERNNORCLM 0 > > #define ALLOC_KERNRCLM 1 > > #define ALLOC_USERRCLM 2 > > #define ALLOC_FALLBACK 3 > > +#define ALLOC_USERZERO 4 > > +#define ALLOC_KERNZERO 5 > > > > Now, 5bits per MAX_ORDER pages. > I think it is simpler to use "char[]" for representing type of memory alloc > type than bitmap. > Possibly, but it would also use up that bit more space. That map could be condensed to 3 bits but would make it that bit (no pun) more complex and difficult to merge. On the other hand, it would be faster to use a char[] as it would be an array-index lookup to get a pageblock type rather than a number of bit operations. So, it depends on what people know to be better in general because I have not measured it to know for a fact. Is it better to use char[] and use array indexes rather than bit operations or is it better to leave it as a bitmap and condense it later when things have settled down? -- Mel Gorman -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org