From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [RFC] Heterogeneous memory management (mirror process address space on a device mmu). Date: Wed, 07 May 2014 17:18:36 +1000 Message-ID: <1399447116.4161.36.camel@pasglop> References: <1399038730-25641-1-git-send-email-j.glisse@gmail.com> <20140506102925.GD11096@twins.programming.kicks-ass.net> <20140506150014.GA6731@gmail.com> <20140506153315.GB6731@gmail.com> <20140506161836.GC6731@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Jerome Glisse , Peter Zijlstra , linux-mm , Linux Kernel Mailing List , linux-fsdevel , Mel Gorman , "H. Peter Anvin" , Andrew Morton , Linda Wang , Kevin E Martin , Jerome Glisse , Andrea Arcangeli , Johannes Weiner , Larry Woodman , Rik van Riel , Dave Airlie , Jeff Law , Brendan Conoboy , Joe Donohue , Duncan Poole , Sherry Cheung , Subhash To: Linus Torvalds Return-path: In-Reply-To: Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Tue, 2014-05-06 at 09:32 -0700, Linus Torvalds wrote: > and what I think a GPU flush has to do is to do the actual flushes > when asked to (because that's what it will need to do to work with a > real TLB eventually), but if there's some crazy asynchronous > acknowledge thing from hardware, it's possible to perhaps wait for > that in the final phase (*before* we free the pages we gathered). Hrm, difficult. We have some pretty strong assumptions that ptep_clear_flush() is fully synchronous as far as I can tell... ie, your trick would work for the unmap case but everything else is still problematic. Ben. -- 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