From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 19 Feb 2008 20:46:03 -0600 From: Robin Holt Subject: Re: [patch] my mmu notifiers Message-ID: <20080220024602.GA11364@sgi.com> References: <20080219084357.GA22249@wotan.suse.de> <20080219135851.GI7128@v2.random> <20080219142725.GA23200@sgi.com> <20080219230427.GB18912@wotan.suse.de> <20080220005206.GP7128@v2.random> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080220005206.GP7128@v2.random> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: Nick Piggin , Jack Steiner , akpm@linux-foundation.org, Robin Holt , Avi Kivity , Izik Eidus , kvm-devel@lists.sourceforge.net, Peter Zijlstra , general@lists.openfabrics.org, Steve Wise , Roland Dreier , Kanoj Sarcar , linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com, Christoph Lameter List-ID: On Wed, Feb 20, 2008 at 01:52:06AM +0100, Andrea Arcangeli wrote: > On Wed, Feb 20, 2008 at 12:04:27AM +0100, Nick Piggin wrote: > > OK (thanks to Robin as well). Now I understand why you are using it, > > but I don't understand why you don't defer new TLBs after the point > > where the linux pte changes. If you can do that, then you look and > > act much more like a TLB from the point of view of the Linux vm. > > Christoph was forced to put the invalidate_range callback _after_ > dropping the PT lock because xpmem has to wait I/O there. But > invalidate_range is called after freeing the VM reference on the pages > so then GRU needed a _range_begin too because GRU has to flush the tlb > before the VM reference on the page is released (xpmem and KVM pin the > pages mapped by the secondary mmu, GRU doesn't). So then > invalidate_range was renamed to invalidate_range_end. Currently, xpmem blocks faults for the range specified at the _begin callout, then shoots down remote TLBs and does the put_page for all the pages in the specified range. The _end callout merely removes the block. We do not do any wait for I/O. By the time we return from the _begin callout, all activity by the remotes is stopped, pages are dereferenced, and future faults are blocked until released by the _end callout. Thanks, Robin -- 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