From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by rv-out-0708.google.com with SMTP id f25so485426rvb.26 for ; Sat, 03 May 2008 21:06:02 -0700 (PDT) Message-ID: <86802c440805032106t4d020838v39aaf93309003cdb@mail.gmail.com> Date: Sat, 3 May 2008 21:06:02 -0700 From: "Yinghai Lu" Subject: Re: [RFC 0/2] Rootmem: boot-time memory allocator In-Reply-To: <20080503175426.GB5292@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080503152502.191599824@symbol.fehenstaub.lan> <20080503175426.GB5292@elte.hu> Sender: owner-linux-mm@kvack.org Return-Path: To: Ingo Molnar Cc: Johannes Weiner , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andi Kleen , Andrew Morton , Linus Torvalds List-ID: On Sat, May 3, 2008 at 10:54 AM, Ingo Molnar wrote: > > * Johannes Weiner wrote: > > > I was spending some time and work on the bootmem allocator the last > > few weeks and came to the conclusion that its current design is not > > appropriate anymore. > > > > As Ingo said in another email, NUMA technologies will become weirder, > > nodes whose PFNs span other nodes for example and it makes bootmem > > code become an unreadable mess. > > > > So I sat down two days ago and rewrote the allocator, here is the > > result: rootmem! > > hehe :-) > > > > The biggest difference to the old design is that there is only one > > bitmap for all PFNs of all nodes together, so the overlapping PFN > > problems simply dissolve and fun like allocations crossing node > > boundaries work implicitely. The new API requires every node used by > > the allocator to be registered and after that the bitmap gets > > allocated and the allocator enabled. > > > > I chose to add a new allocator rather than replacing bootmem at once > > because that would have required all callsites to switch in one go, > > which would be a lot. The new allocator can be adopted more slowly > > and I added a compatibility API for everything besides actually > > setting up the allocator. When the last user dies, bootmem can be > > dropped completely (including pgdat->bdata, whee..) > > > > The main ideas from bootmem have been stolen^W preserved but the new > > design allowed me to shrink the code a lot and express things more > > simple and clear: > > > > $ sloc.awk < mm/bootmem.c > > 455 lines of code, 65 lines of comments (520 lines total) > > > > $ sloc.awk < mm/rootmem.c > > 243 lines of code, 96 lines of comments (339 lines total) > > amazing! > > i'd still suggest to keep it all named bootmem though :-/ How about > bootmem2.c and then renaming it back to bootmem.c, once the last user is > gone? That would save people from having to rename whole chapters in > entire books ;-) for spanning support node0:0-2g, 4-6g; node1: 2-4g, 6-8g, could have some problem. +/* + * rootmem_register_node - register a node to rootmem + * @nid: node id + * @start: first pfn on the node + * @end: first pfn after the node + * + * This function must not be called anymore if the allocator + * is already up and running (rootmem_setup() has been called). + */ +void __init rootmem_register_node(int nid, unsigned long start, + unsigned long end) +{ + BUG_ON(rootmem_functional); + + if (start < rootmem_min_pfn) + rootmem_min_pfn = start; + if (end > rootmem_max_pfn) + rootmem_max_pfn = end; + + rootmem_node_pages[nid] = end - start; + rootmem_node_offsets[nid] = start; + rootmem_nr_nodes++; +} could change rootmem_node_pages/offsets to be struct array with offset, pages, and nid. and every node could several struct. and whole array should be sorted with nid. YH -- 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