From mboxrd@z Thu Jan 1 00:00:00 1970 From: Borislav Petkov Subject: Re: [PATCH 01/11] resource: Add System RAM resource type Date: Wed, 16 Dec 2015 19:17:12 +0100 Message-ID: <20151216181712.GJ29775@pd.tnic> References: <1450136246-17053-1-git-send-email-toshi.kani@hpe.com> <20151216122642.GE29775@pd.tnic> <1450280642.29051.76.camel@hpe.com> <20151216154916.GF29775@pd.tnic> <1450283759.20148.11.camel@hpe.com> <20151216174523.GH29775@pd.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Dan Williams Cc: Toshi Kani , Andrew Morton , linux-arch@vger.kernel.org, Linux MM , "linux-kernel@vger.kernel.org" , Linus Torvalds , "Rafael J. Wysocki" List-Id: linux-arch.vger.kernel.org On Wed, Dec 16, 2015 at 09:52:37AM -0800, Dan Williams wrote: > It's possible that as far as the resource table is concerned the > resource type might just be "reserved". It may not be until after a > driver loads that we discover the memory range type. The identifying > string is driver specific at that point. So how many types are we talking about here? Because I don't find a whole lot: $ git grep -E "(walk_iomem_res|find_next_iomem_res|region_intersects)" -- *.c | grep -Eo '\".*\"' "GART" "ACPI Tables" "ACPI Non-volatile Storage" "Crash kernel" "System RAM" "System RAM" "System RAM" An int type could contain 2^32 different types. > All this to say that with strcmp we can search for any custom type . > Otherwise I think we're looking at updating the request_region() > interface to take a type parameter. That makes strcmp capability more > attractive compared to updating a potentially large number of > request_region() call sites. Right, but I don't think that @name param to request_region() was ever meant to be mis-used as a matching attribute when iterating over the resource types. Now, imagine you have to do this pretty often. Which is faster: a strcmp() or an int comparison...? Even if this cannot be changed easily/in one go, maybe we should at least think about starting doing it right so that the strcmp() "fun" is phased out gradually... -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.skyhub.de ([78.46.96.112]:42837 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754956AbbLPSRV (ORCPT ); Wed, 16 Dec 2015 13:17:21 -0500 Date: Wed, 16 Dec 2015 19:17:12 +0100 From: Borislav Petkov Subject: Re: [PATCH 01/11] resource: Add System RAM resource type Message-ID: <20151216181712.GJ29775@pd.tnic> References: <1450136246-17053-1-git-send-email-toshi.kani@hpe.com> <20151216122642.GE29775@pd.tnic> <1450280642.29051.76.camel@hpe.com> <20151216154916.GF29775@pd.tnic> <1450283759.20148.11.camel@hpe.com> <20151216174523.GH29775@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Dan Williams Cc: Toshi Kani , Andrew Morton , linux-arch@vger.kernel.org, Linux MM , "linux-kernel@vger.kernel.org" , Linus Torvalds , "Rafael J. Wysocki" Message-ID: <20151216181712.wb86g5MJXumONs7gIUDyu-Hn9GGympFbGrlCKsG3lr4@z> On Wed, Dec 16, 2015 at 09:52:37AM -0800, Dan Williams wrote: > It's possible that as far as the resource table is concerned the > resource type might just be "reserved". It may not be until after a > driver loads that we discover the memory range type. The identifying > string is driver specific at that point. So how many types are we talking about here? Because I don't find a whole lot: $ git grep -E "(walk_iomem_res|find_next_iomem_res|region_intersects)" -- *.c | grep -Eo '\".*\"' "GART" "ACPI Tables" "ACPI Non-volatile Storage" "Crash kernel" "System RAM" "System RAM" "System RAM" An int type could contain 2^32 different types. > All this to say that with strcmp we can search for any custom type . > Otherwise I think we're looking at updating the request_region() > interface to take a type parameter. That makes strcmp capability more > attractive compared to updating a potentially large number of > request_region() call sites. Right, but I don't think that @name param to request_region() was ever meant to be mis-used as a matching attribute when iterating over the resource types. Now, imagine you have to do this pretty often. Which is faster: a strcmp() or an int comparison...? Even if this cannot be changed easily/in one go, maybe we should at least think about starting doing it right so that the strcmp() "fun" is phased out gradually... -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply.