From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id CC6316B0044 for ; Wed, 4 Nov 2009 15:40:11 -0500 (EST) Date: Wed, 4 Nov 2009 13:40:08 -0700 From: Alex Chiang Subject: Re: [PATCH] page-types: decode flags directly from command line Message-ID: <20091104204008.GA8211@ldl.fc.hp.com> References: <20091103225441.GB4087@grease> <20091104121832.GB26504@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091104121832.GB26504@localhost> Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andi Kleen , "Li, Haicheng" List-ID: Hi Fengguang, * Wu Fengguang : > On Wed, Nov 04, 2009 at 06:54:41AM +0800, Alex Chiang wrote: > > Why is this useful? For instance, if you're using memory hotplug > > and see this in /var/log/messages: > > > > kernel: removing from LRU failed 3836dd0/1/1e00000000000400 > > > > It would be nice to decode those page flags without staring at > > the source. > > In fact it's more than decode - encoding is also possible with the > _same_ code! So maybe "-d" and help message will not be all that > appropriate. I'm sorry, I don't understand this use case, so I'm not sure what you're asking me to do. You're saying that a use case would be something like: ./page-types --encode referenced,mmap 0x0000000000000004 ? If that's what you're asking for, I guess I'm not sure why that's so useful, but then again, I'm a vm n00b so there are probably lots of things I don't understand. ;) > > Example usage and output: > > > > linux-2.6/Documentation/vm$ ./page-types -d 0x1e00000000000400 > > flags page-count MB symbolic-flags long-symbolic-flags > > 0x1e00000000000400 1 0 __________B_______________________buddy > > total 1 0 > > The output is a bit redundant - so does the code. Could you simplify > them a bit? Well, the code is redundant, but add_page() / show_summary() is a simple sequence. In contrast, I think I'd have to modify walk_addr_ranges() and maybe walk_pfn() to do something special when we don't really want to do any address space walking, and simply want to decode/encode some user input. Maybe I don't understand you fully? Could you give me a better idea of what you're looking for? As for the output, I'm just reusing show_summary(). Maybe we don't need the flags, page-count, and MB columns, but again, the patch would be more intrusisive because we'd have to teach show_summary() about the special case. Anyway, I'm happy to make changes closer to what you're looking for, but I'd like some more guidance as to what you're expecting. Thanks, /ac -- 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