From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f182.google.com (mail-wi0-f182.google.com [209.85.212.182]) by kanga.kvack.org (Postfix) with ESMTP id 8379D6B0035 for ; Thu, 24 Apr 2014 07:04:15 -0400 (EDT) Received: by mail-wi0-f182.google.com with SMTP id d1so848783wiv.3 for ; Thu, 24 Apr 2014 04:04:15 -0700 (PDT) Received: from pandora.arm.linux.org.uk (pandora.arm.linux.org.uk. [2001:4d48:ad52:3201:214:fdff:fe10:1be6]) by mx.google.com with ESMTPS id ek7si9086574wib.117.2014.04.24.04.04.13 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 24 Apr 2014 04:04:14 -0700 (PDT) Date: Thu, 24 Apr 2014 12:03:21 +0100 From: Russell King - ARM Linux Subject: Re: [PATCH V2 0/5] Huge pages for short descriptors on ARM Message-ID: <20140424110321.GN26756@n2100.arm.linux.org.uk> References: <1397648803-15961-1-git-send-email-steve.capper@linaro.org> <20140424102229.GA28014@linaro.org> <20140424103639.GC19564@arm.com> <20140424104232.GK26756@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Steve Capper Cc: Will Deacon , "akpm@linux-foundation.org" , Catalin Marinas , "robherring2@gmail.com" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "gerald.schaefer@de.ibm.com" On Thu, Apr 24, 2014 at 11:55:56AM +0100, Steve Capper wrote: > On 24 April 2014 11:42, Russell King - ARM Linux wrote: > > On Thu, Apr 24, 2014 at 11:36:39AM +0100, Will Deacon wrote: > >> I guess I'm after some commitment that this is (a) useful to somebody and > >> (b) going to be tested regularly, otherwise it will go the way of things > >> like big-endian, where we end up carrying around code which is broken more > >> often than not (although big-endian is more self-contained). > > > > It may be something worth considering adding to my nightly builder/boot > > testing, but I suspect that's impractical as it probably requires a BE > > userspace, which would then mean that the platform can't boot LE. > > > > I suspect that we will just have to rely on BE users staying around and > > reporting problems when they occur. > > The huge page support is for standard LE, I think Will was saying that > this will be like BE if no-one uses it. We're not saying that. What we're asking is this: *Who* is using hugepages today? What we're then doing is comparing it to the situation we have today with BE, where BE support is *always* getting broken because no one in the main community tests it - not even a build test, nor a boot test which would be required to find the problems that (for example) cropped up in the last merge window. > It's somewhat unfair to compare huge pages on short descriptors with > BE. For a start, the userspace that works with LPAE will work on the > short-descriptor kernel too. That sounds good, but the question is how does this get tested by facilities such as my build/boot system, or Olof/Kevin's system? Without that, it will find itself in exactly the same situation that BE is in, where problems aren't found until after updates are merged into Linus' tree. -- FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly improving, and getting towards what was expected from it. -- 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