From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 24 Apr 2008 04:08:28 +0200 From: Nick Piggin Subject: Re: [patch 00/18] multi size, and giant hugetlb page support, 1GB hugetlb for x86 Message-ID: <20080424020828.GA7101@wotan.suse.de> References: <20080423015302.745723000@nick.local0.net> <480EEDD9.2010601@firstfloor.org> <20080423153404.GB16769@wotan.suse.de> <20080423154652.GB29087@one.firstfloor.org> <20080423155338.GF16769@wotan.suse.de> <20080423185223.GE10548@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080423185223.GE10548@us.ibm.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Nishanth Aravamudan Cc: Andi Kleen , akpm@linux-foundation.org, linux-mm@kvack.org, kniht@linux.vnet.ibm.com, abh@cray.com, wli@holomorphy.com List-ID: On Wed, Apr 23, 2008 at 11:52:23AM -0700, Nishanth Aravamudan wrote: > On 23.04.2008 [17:53:38 +0200], Nick Piggin wrote: > > > It's not fully compatible. And that is bad. > > > > It is fully compatible because if you don't actually ask for any new > > option then you don't get it. What you see will be exactly unchanged. > > If you ask for _only_ 1G pages, then this new scheme is very likely to > > work with well written applications wheras if you also print out the 2MB > > legacy values first, then they have little to no chance of working. > > > > Then if you want legacy apps to use 2MB pages, and new ones to use 1G, > > then you ask for both and get the 2MB column printed in /proc/meminfo > > (actually it can probably get printed 2nd if you ask for 2MB pages > > after asking for 1G pages -- that is something I'll fix). > > Yep, the "default hugepagesz" was something I was going to ask about. I > believe hugepagesz= should function kind of like console= where the > order matters if specified multiple times for where /dev/console points. > I agree with you that hugepagesz=XX hugepagesz=YY implies XX is the > default, and YY is the "other", regardless of their values, and that is > how they should be presented in meminfo. OK, that would be fine. I was going to do it the other way and make 2M always come first. However so long as we document as such the command line parameters, I don't see why we couldn't have this extra flexibility (and that means I shouldn't have to write any more code ;)) -- 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