From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id C375C6B0209 for ; Thu, 29 Apr 2010 14:59:23 -0400 (EDT) Message-ID: <4BD9D702.90209@redhat.com> Date: Thu, 29 Apr 2010 21:59:14 +0300 From: Avi Kivity MIME-Version: 1.0 Subject: Re: Frontswap [PATCH 0/4] (was Transcendent Memory): overview References: <4BD16D09.2030803@redhat.com> <4BD1A74A.2050003@redhat.com> <4830bd20-77b7-46c8-994b-8b4fa9a79d27@default> <4BD1B427.9010905@redhat.com> <4BD1B626.7020702@redhat.com> <5fa93086-b0d7-4603-bdeb-1d6bfca0cd08@default> <4BD3377E.6010303@redhat.com> <1c02a94a-a6aa-4cbb-a2e6-9d4647760e91@default4BD43033.7090706@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Dan Magenheimer Cc: Pavel Machek , linux-kernel@vger.kernel.org, linux-mm@kvack.org, jeremy@goop.org, hugh.dickins@tiscali.co.uk, ngupta@vflare.org, JBeulich@novell.com, chris.mason@oracle.com, kurt.hackel@oracle.com, dave.mccracken@oracle.com, npiggin@suse.de, akpm@linux-foundation.org, riel@redhat.com List-ID: On 04/29/2010 05:42 PM, Dan Magenheimer wrote: >> >> Yes, and that set of hooks is new API, right? >> > Well, no, if you define API as "application programming interface" > this is NOT exposed to userland. If you define API as a new > in-kernel function call, yes, these hooks are a new API, but that > is true of virtually any new code in the kernel. If you define > API as some new interface between the kernel and a hypervisor, > yes, this is a new API, but it is "optional" at several levels > so that any hypervisor (e.g. KVM) can completely ignore it. > The concern is not with the hypervisor, but with Linux. More external APIs reduce our flexibility to change things. > So please let's not argue about whether the code is a "new API" > or not, but instead consider whether the concept is useful or not > and if useful, if there is or is not a cleaner way to implement it. > I'm convinced it's useful. The API is so close to a block device (read/write with key/value vs read/write with sector/value) that we should make the effort not to introduce a new API. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain. -- 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