From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id 476F16B0005 for ; Wed, 22 Jun 2016 16:10:22 -0400 (EDT) Received: by mail-lf0-f72.google.com with SMTP id a4so42558757lfa.1 for ; Wed, 22 Jun 2016 13:10:22 -0700 (PDT) Received: from mail-lf0-x229.google.com (mail-lf0-x229.google.com. [2a00:1450:4010:c07::229]) by mx.google.com with ESMTPS id 36si1206812lfv.21.2016.06.22.13.10.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Jun 2016 13:10:20 -0700 (PDT) Received: by mail-lf0-x229.google.com with SMTP id h129so81970001lfh.1 for ; Wed, 22 Jun 2016 13:10:20 -0700 (PDT) Date: Wed, 22 Jun 2016 23:10:18 +0300 From: Cyrill Gorcunov Subject: Re: JITs and 52-bit VA Message-ID: <20160622201018.GC2045@uranus.lan> References: <4A8E6E6D-6CF7-4964-A62E-467AE287D415@linaro.org> <576AA67E.50009@codeaurora.org> <20160622191843.GA2045@uranus.lan> <576AED88.6040805@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <576AED88.6040805@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Andy Lutomirski , Christopher Covington , Maxim Kuvyrkov , Linaro Dev Mailman List , Arnd Bergmann , Mark Brown , "linux-mm@kvack.org" , Dmitry Safonov On Wed, Jun 22, 2016 at 12:56:56PM -0700, Dave Hansen wrote: > >> > +1. Also it might be (not sure though, just guessing) suitable to do such > >> > thing via memory cgroup controller, instead of carrying this limit per > >> > each process (or task structure/vma or mm). > > I think we'll want this per mm. After all, a high-VA-limit-aware bash > > should be able run high-VA-unaware programs without fiddling with > > cgroups. > > Yeah, cgroups don't make a lot of sense. cgroups make sense in terms of shriking data: we only need to setup the limit once and every process lives in the cgroup get the limit, no need to carry it per every mm. So I guessed it might be usefull. > On x86, the 48-bit virtual address is even hard-coded in the ABI[1]. So > we can't change *any* program's layout without either breaking the ABI > or having it opt in. > > But, we're also lucky to only have one VA layout since day one. > > 1. www.x86-64.org/documentation/abi.pdf - a??... Therefore, conforming > processes may only use addresses from 0x00000000 00000000 to 0x00007fff > ffffffff .a?? Cyrill -- 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