From owner-freebsd-ppc@FreeBSD.ORG Mon Dec 10 00:54:13 2012 Return-Path: Delivered-To: powerpc@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 5623B2D1 for ; Mon, 10 Dec 2012 00:54:13 +0000 (UTC) (envelope-from imp@bsdimp.com) Received: from mail-ie0-f182.google.com (mail-ie0-f182.google.com [209.85.223.182]) by mx1.freebsd.org (Postfix) with ESMTP id EDFD58FC13 for ; Mon, 10 Dec 2012 00:54:11 +0000 (UTC) Received: by mail-ie0-f182.google.com with SMTP id s9so8337589iec.13 for ; Sun, 09 Dec 2012 16:54:11 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=sender:subject:mime-version:content-type:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to:x-mailer :x-gm-message-state; bh=NQ/SFUzHRS12x8NX6tNgjKotHD2QRO5QpoGfvtwLETk=; b=IZqjn2rehj080x/2lBqYtNBgEktGY9SXvYlVJhEX0y7WZuZ2Zyvg4MtnT8qbtRbSlQ GvlQHcusyB248pgEiTZGs2HLKam0mo9k4qVQoJsYyqtQVyNNSerffK5RZwF9QJuaf536 SFWHocn7zNLyLT9dWmffmtFDDa6stDLSJqDMOSheU6vMwXFEX7QVL797NKd3QfJg8DqN DlN0R4T7G5fScPBB5cXB+EiYBKzqV53aIAr7I6SYlAWtgeJDdxuraf7o6fSNzKq3gRZW ozzrLVgkMmXf6ULgYjCA3BHNMrJtmxtA5rXpMOh9q4/Ztx7utXdb4Qi31AweY3USFbuO 6k9g== Received: by 10.50.157.130 with SMTP id wm2mr7911478igb.0.1355100851225; Sun, 09 Dec 2012 16:54:11 -0800 (PST) Received: from 53.imp.bsdimp.com (50-78-194-198-static.hfc.comcastbusiness.net. [50.78.194.198]) by mx.google.com with ESMTPS id l8sm5263808igo.13.2012.12.09.16.54.08 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 09 Dec 2012 16:54:10 -0800 (PST) Sender: Warner Losh Subject: Re: Call for testing and review, busdma changes Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: text/plain; charset=us-ascii From: Warner Losh In-Reply-To: Date: Sun, 9 Dec 2012 17:54:07 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: References: <1355077061.87661.320.camel@revolution.hippie.lan> To: Jeff Roberson X-Mailer: Apple Mail (2.1085) X-Gm-Message-State: ALoCoQlBA2TmZ7zutFaD7t7va1AUqqr2wy5SBj8eAq2hHOmaZiBNW7vLrrXwh0oLXU7doY1e4+o8 X-Mailman-Approved-At: Mon, 10 Dec 2012 01:02:01 +0000 Cc: Ian Lepore , powerpc@freebsd.org, marcel@freebsd.org, mips@freebsd.org, mav@freebsd.org, scottl@freebsd.org, attilio@freebsd.org, kib@freebsd.org, sparc64@freebsd.org, arm@freebsd.org X-BeenThere: freebsd-ppc@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Porting FreeBSD to the PowerPC List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Dec 2012 00:54:13 -0000 [[ looks like Ian answered the other questions ]] On Dec 9, 2012, at 11:48 AM, Jeff Roberson wrote: >>> The next step is to allow for dma loading of physical addresses. = This >>> will permit unmapped I/O. Which is a significant performance = optimization >>> targeted for 10.0. >>=20 >> This sounds scary for arm and mips, or more specifically for VIVT = cache >> platforms that can only do a sync based on virtual addresses. Can = you >> talk some more about the plans for this? >=20 > It will be for addresses which were never mapped into kva. To support = unmaapped io. There will only be a need for bounce pages, no syncing. If there's a virtual mapping at all for the page (not just a kva), then = we need to flush/invalidate cache for those pages for safety unless we = know for sure there's nothing in the cache. It these are pages that = have never been mapped (say for zero copy between storage and network = controllers), then there won't be a problem. The whole reason for cache = jockeying is to make sure that any pending writes to the data are = flushed, and that any cached notion of the pages are invalidated once = the read is done. This is more important for mbuf operations, = operations with the USB stack or anything else that marshals data it = generates to be consumed by the stack/hardware. Warner