From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 7486E6B01F2 for ; Thu, 22 Apr 2010 11:49:00 -0400 (EDT) MIME-Version: 1.0 Message-ID: <53c81c97-b30f-4081-91a1-7cef1879c6fa@default> Date: Thu, 22 Apr 2010 08:48:31 -0700 (PDT) From: Dan Magenheimer Subject: RE: Frontswap [PATCH 0/4] (was Transcendent Memory): overview References: <20100422134249.GA2963@ca-server1.us.oracle.com 4BD06B31.9050306@redhat.com> In-Reply-To: <4BD06B31.9050306@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Avi Kivity Cc: 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: > > a synchronous concurrency-safe page-oriented pseudo-RAM device (such > > : > > conform to certain policies as follows: >=20 > How baked in is the synchronous requirement? Memory, for example, can > be asynchronous if it is copied by a dma engine, and since there are > hardware encryption engines, there may be hardware compression engines > in the future. Thanks for the comment! Synchronous is required, but likely could be simulated by ensuring all coherency (and concurrency) requirements are met by some intermediate "buffering driver" -- at the cost of an extra page copy into a buffer and overhead of tracking the handles (poolid/inode/index) of pages in the buffer that are "in flight". This is an approach we are considering to implement an SSD backend, but hasn't been tested yet so, ahem, the proof will be in the put'ing. ;-) Dan -- 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