From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikita Danilov MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16129.33029.930495.661244@laputa.namesys.com> Date: Tue, 1 Jul 2003 16:39:33 +0400 Subject: Re: 2.5.73-mm2 In-Reply-To: <20030701110858.GF26348@holomorphy.com> References: <20030701105134.GE26348@holomorphy.com> <20030701110858.GF26348@holomorphy.com> Sender: owner-linux-mm@kvack.org Return-Path: To: William Lee Irwin III Cc: Hugh Dickins , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: William Lee Irwin III writes: > On Tue, 1 Jul 2003, William Lee Irwin III wrote: > >> Well, I was mostly looking for getting handed back 0 when lowmem is > >> empty; I actually did realize they didn't give entirely accurate counts > >> of free lowmem pages. > > On Tue, Jul 01, 2003 at 12:08:03PM +0100, Hugh Dickins wrote: > > I'm not pleading for complete accuracy, but nr_free_buffer_pages() > > will never hand back 0 (if your system managed to boot). > > It's a static count of present_pages (adjusted), not of > > free pages. Or am I misreading nr_free_zone_pages()? > > You're right. Wow, that's even more worse than I suspected. > Another thing is that if one boots with mem=X, nr_free_pagecache_pages() returns X. However part of X (occupied by kernel image, etc) is not part of any zone. As a result, zone actually contains fewer pages than reported by nr_free_pagecache_pages(). With X small enough (comparable with kernel image size, for example) this can confuse balance_dirty_pages() enough so that throttling would never start, and VM will oom_kill(). > > -- wli Nikita. -- 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