Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932655AbXKOThp (ORCPT ); Thu, 15 Nov 2007 14:37:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760281AbXKOThg (ORCPT ); Thu, 15 Nov 2007 14:37:36 -0500 Received: from fxip-0047f.externet.hu ([88.209.222.127]:48439 "EHLO dorka.pomaz.szeredi.hu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753039AbXKOThf (ORCPT ); Thu, 15 Nov 2007 14:37:35 -0500 To: a.p.zijlstra@chello.nl CC: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org In-reply-to: <1195154530.22457.16.camel@lappy> (message from Peter Zijlstra on Thu, 15 Nov 2007 20:22:10 +0100) Subject: Re: [RFC] fuse writable mmap design References: <1195154530.22457.16.camel@lappy> Message-Id: From: Miklos Szeredi Date: Thu, 15 Nov 2007 20:37:27 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1009 Lines: 24 > I'm somewhat confused by the complexity. Currently we can already have a > lot of dirty pages from FUSE (up to the per BDI dirty limit - so > basically up to the total dirty limit). > > How is having them dirty from mmap'ed writes different? Nope, fuse never had dirty pages. It does normal writes synchronously, just updating the cache. The dirty accounting and then the per-bdi throttling basically made it possible _at_all_ to have a chance at a writepage implementation which is not deadlocky (so thanks for those ;). But there's still the throttle_vm_writeout() thing, and the other places where the kernel is waiting for a write to complete, which just cannot be done within a constrained time if an unprivileged userspace process is involved. Miklos - 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/