From mboxrd@z Thu Jan 1 00:00:00 1970 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: owner-linux-mm@kvack.org Return-Path: 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 List-ID: > 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, 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