Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755022AbYGGMJ0 (ORCPT ); Mon, 7 Jul 2008 08:09:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753356AbYGGMJS (ORCPT ); Mon, 7 Jul 2008 08:09:18 -0400 Received: from py-out-1112.google.com ([64.233.166.177]:58162 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753316AbYGGMJS (ORCPT ); Mon, 7 Jul 2008 08:09:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:references:date:in-reply-to:message-id :user-agent:mime-version:content-type; b=fHt1t1iaH8sXrvV3vgNhto7LIxtMs7M55b6LxfBCX9CSc6/deoj84hz8uUn/CKA+LH Uh9ZUvCCH+cS9c8Uox5wTXibrurJtCyraszuDvUX+DVg696Fh5DpTrfkebJCOVG/8XIE p5F6MkkAosEu+Z5S73amAlbxBDwkOp199CEEE= From: Vitaly Mayatskikh To: Linus Torvalds Cc: Vitaly Mayatskikh , Andi Kleen , linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: [PATCH 1/2] Introduce copy_user_handle_tail routine References: <486B8B6C.2050109@firstfloor.org> Date: Mon, 07 Jul 2008 14:09:10 +0200 In-Reply-To: (Linus Torvalds's message of "Wed, 2 Jul 2008 19:35:11 -0700 (PDT)") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1120 Lines: 26 Linus Torvalds writes: > Now, the stuff that comes *before* that point is the "try to fix up one > byte at a time" thing, which I'd like to be simple and dumb. At least to > start with. Just to be clear: do these patches are good enough now (to start with)? Or, may be, it needs to be further improved? > Of course, I also suspect that *eventually* we might want to make it > smarter and more complex. For example, while performance isn't a primary > issue, we might want to eventually avoid having to do _two_ faults (once > in the fast unrolled or word-at-a-time loop, and once in the byte-for-byte > one), by limiting the byte-for-byte one to be within a page, but that > would be a "future enhancement" thing. Btw, how much does it cost to CPU to do a fault? Can it be compared with average time of find_vma()? -- wbr, Vitaly -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/