Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 7 Mar 2001 13:23:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 7 Mar 2001 13:23:23 -0500 Received: from neon-gw.transmeta.com ([209.10.217.66]:29958 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id ; Wed, 7 Mar 2001 13:23:02 -0500 To: linux-kernel@vger.kernel.org From: torvalds@transmeta.com (Linus Torvalds) Subject: Re: Hashing and directories Date: 7 Mar 2001 10:21:56 -0800 Organization: Transmeta Corporation Message-ID: <985u84$2ku$1@penguin.transmeta.com> In-Reply-To: <000201c0a71f$3a48fae0$5517fea9@local> <20010307171020.A10607@pcep-jamie.cern.ch> <003701c0a722$f6b02700$5517fea9@local> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In article <003701c0a722$f6b02700$5517fea9@local>, Manfred Spraul wrote: > >exec_mmap currenly avoids mm_alloc()/activate_mm()/mm_drop() for single >threaded apps, and that would become impossible. >I'm not sure how expensive these calls are. They aren't that expensive: activate_mm() needs to flush the TLB, but we do that anyway in the re-use case too, so on the whole the expense is limited to having to do the extra allocation. That expense might be at least partially offset by being able to do some things more simply - right now the mm re-use case actually has to be more careful than I really like for security and protection reasons, for example. We've had bugs in this area before - simplifying it would be nice. And it also gets rid of the special cases. I don't think the patches to do this should be all that huge, but who knows? It's not a trivial part of the kernel. Linus - 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/