From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S271927AbTGRW5b (ORCPT ); Fri, 18 Jul 2003 18:57:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S271930AbTGRW5b (ORCPT ); Fri, 18 Jul 2003 18:57:31 -0400 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:30914 "EHLO dualathlon.random") by vger.kernel.org with ESMTP id S271927AbTGRW50 (ORCPT ); Fri, 18 Jul 2003 18:57:26 -0400 Date: Sat, 19 Jul 2003 01:12:30 +0200 From: Andrea Arcangeli To: William Lee Irwin III , Christoph Hellwig , linux-kernel@vger.kernel.org Subject: Re: 2.4.22pre6aa1 Message-ID: <20030718231230.GA19045@dualathlon.random> References: <20030717102857.GA1855@dualathlon.random> <20030718191853.A11052@infradead.org> <20030718222750.GL3928@dualathlon.random> <20030718224824.GP15452@holomorphy.com> <20030718225328.GQ3928@dualathlon.random> <20030718230431.GQ15452@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030718230431.GQ15452@holomorphy.com> User-Agent: Mutt/1.4i X-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 X-PGP-Key: 1024R/CB4660B9 CC A0 71 81 F4 A0 63 AC C0 4B 81 1D 8C 15 C8 E5 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 18, 2003 at 04:04:31PM -0700, William Lee Irwin III wrote: > On Sat, Jul 19, 2003 at 12:53:28AM +0200, Andrea Arcangeli wrote: > > I tend to think the creation/destruction will be the most noticeable > > performance difference in practice. allocating 42G in a single block > > will take a bit of time ;). I'm not necessairly worse or unacceptable, > > but it's different. And I feel I've to retain the bigpages= API (as an > > API not as in implementation) anyways. Furthmore I'm unsure if hugtlbfs > > is relaxed like the shm-largpeage patch is, I mean, it should be > > possible to mmap the stuff with 4k granularty too, or stuff could break > > due that change of API too. > > I've just not gotten feedback about creation and destruction; I get the > impression it's an uncommon operation. It's uncommon of course. A 42G allocated all at once, may take a while and 48G works flawlessy at peak performance w/o 4:4. I support as much as 64G all in a single shmfs file backed by bigpages (and it won't run out of memory with a 64G box either, even with the 3:1 mapping) > The alignment etc. considerations are bits I probably can't get merged. =( so the apps will need changes and a kernel API way to know the hardware page size provided by hugetlbfs (though they could probe for it with many tries). > Most of the work I did was trying to get the preexisting semantics into > more standard-looking API's, e.g. vfs ops and standard-ish sysv shm. yes. Andrea