From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <43FE4D45.2040209@jp.fujitsu.com> Date: Fri, 24 Feb 2006 09:03:17 +0900 From: KAMEZAWA Hiroyuki MIME-Version: 1.0 Subject: Re: [RFC] memory-layout-free zones (for review) [3/3] fix for_each_page_in_zone References: <20060223180023.396d2cfe.kamezawa.hiroyu@jp.fujitsu.com> <1140718333.8697.69.camel@localhost.localdomain> In-Reply-To: <1140718333.8697.69.camel@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: linux-mm List-ID: Dave Hansen wrote: > I know we don't use this function _too_ much , but it would probably be > nice to make it a little smarter than "i++". We can be pretty sure, at > least with SPARSEMEM that the granularity is larger than that. We can > probably leave it until it gets to be a real problem. Yes, SPARSEMEM can skip PAGES_PER_SECTION pages if !pfn_valid() > > I was also trying to think if a binary search is appropriate here. I > guess it depends on whether we allow the zones to have overlapping pfn > ranges, which I _think_ is one of the goals from these patches. Any > thoughts? > What I'm thinking of is to allow zones to have overlapping pfn ranges. Showing benefit of it (by patch) is difficult now but I think it's sane direction. > Oh, and I noticed the "pgdat->zone_spanned_pages" bit. Did you compile > this? ;) > No (>_< >> +static inline struct page *next_page_in_zone(struct page *page, >> + struct zone *zone) >> +{ >> + struct pglist_data *pgdat; >> + unsigned long start_pfn; >> + unsigned long i; >> + >> + if (!populated_zone(zone)) >> + return NULL; >> + pgdat = zone->zone_pgdat; >> + start_pfn = pgdat->node_start_pfn; >> + i = page_to_pfn(page) - start_pfn; >> + >> + for (i = i + 1; i < pgdat->node_spanned_pages; i++) { >> + if (pfn_vlaid(start_pfn + i) && page_zone(page) == zone) >> + break; >> + } >> + if (i == pgdat->node_spanned_pages) >> + return NULL; >> + return pfn_to_page(start_pfn + i); >> +} > > Same comment, BTW, about code sharing. Is it something we want to or > can do with these? > Hmm...I can't find it. I'll rewrite this code as out-of-line function and add optimizaion by its memory_model, and do more cleanup. I'll post these again to -mm before going lkml, and will do compile them in the next time.... -- Kame -- 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: email@kvack.org