From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Stephen C. Tweedie" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <14417.1440.795510.93176@dukat.scot.redhat.com> Date: Fri, 10 Dec 1999 13:52:32 +0000 (GMT) Subject: Re: Getting big areas of memory, in 2.3.x? In-Reply-To: References: <384F17BA.174B4C6D@mandrakesoft.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Ingo Molnar Cc: Jeff Garzik , Alan Cox , Linux Kernel List , linux-mm@kvack.org, Stephen Tweedie List-ID: Hi, On Thu, 9 Dec 1999 13:25:00 +0100 (CET), Ingo Molnar said: > hm, does anyone have any conceptual problem with a new > allocate_largemem(pages) interface in page_alloc.c? It's not > terribly hard to scan all bitmaps for available RAM and mark the > large memory area allocated and remove all pages from the > freelists. Even better: the zoned allocator makes it pretty easy to reserve (say) the top 25% of memory for use only by freeable (ie. page cache and anonymous) pages: just make a separate zone for that. If there is memory that you know you can reshuffle, then a slow, swapout-style exhaustive VM search will eventually let you allocate any page you want from that zone (barring only mlock()ed pages). That's maybe more work than we want for a problem which may disappear eventually of its own accord: a lot of AGP chipsets these days have a GART which is visible from the PCI side, and that lets you map discontiguous physical pages into a virtual region which looks contiguous to the PCI hardware. There's similar hardware on the Sparc and Alpha PCI boxes (is it universal on PCI buses on those platforms?) --Stephen -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/