Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751972AbaDAWtn (ORCPT ); Tue, 1 Apr 2014 18:49:43 -0400 Received: from mail-oa0-f42.google.com ([209.85.219.42]:45835 "EHLO mail-oa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751498AbaDAWtl (ORCPT ); Tue, 1 Apr 2014 18:49:41 -0400 MIME-Version: 1.0 In-Reply-To: <20140401144801.603c288674ab8f417b42a043@linux-foundation.org> References: <1396235199.2507.2.camel@buesod1.americas.hpqcorp.net> <20140331143217.c6ff958e1fd9944d78507418@linux-foundation.org> <1396306773.18499.22.camel@buesod1.americas.hpqcorp.net> <20140331161308.6510381345cb9a1b419d5ec0@linux-foundation.org> <1396308332.18499.25.camel@buesod1.americas.hpqcorp.net> <20140331170546.3b3e72f0.akpm@linux-foundation.org> <1396371699.25314.11.camel@buesod1.americas.hpqcorp.net> <1396377083.25314.17.camel@buesod1.americas.hpqcorp.net> <1396386062.25314.24.camel@buesod1.americas.hpqcorp.net> <20140401142947.927642a408d84df27d581e36@linux-foundation.org> <20140401144801.603c288674ab8f417b42a043@linux-foundation.org> From: KOSAKI Motohiro Date: Tue, 1 Apr 2014 18:49:21 -0400 Message-ID: Subject: Re: [PATCH] ipc,shm: increase default size for shmmax To: Andrew Morton Cc: Davidlohr Bueso , Manfred Spraul , aswin@hp.com, LKML , "linux-mm@kvack.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 1, 2014 at 5:48 PM, Andrew Morton wrote: > On Tue, 1 Apr 2014 17:41:54 -0400 KOSAKI Motohiro wrote: > >> >> > Hmmm so 0 won't really work because it could be weirdly used to disable >> >> > shm altogether... we cannot go to some negative value either since we're >> >> > dealing with unsigned, and cutting the range in half could also hurt >> >> > users that set the limit above that. So I was thinking of simply setting >> >> > SHMMAX to ULONG_MAX and be done with it. Users can then set it manually >> >> > if they want a smaller value. >> >> > >> >> > Makes sense? >> >> >> >> I don't think people use 0 for disabling. but ULONG_MAX make sense to me too. >> > >> > Distros could have set it to [U]LONG_MAX in initscripts ten years ago >> > - less phone calls, happier customers. And they could do so today. >> > >> > But they haven't. What are the risks of doing this? >> >> I have no idea really. But at least I'm sure current default is much worse. >> >> 1. Solaris changed the default to total-memory/4 since Solaris 10 for DB. >> http://www.postgresql.org/docs/9.1/static/kernel-resources.html >> >> 2. RHEL changed the default to very big size since RHEL5 (now it is >> 64GB). Even tough many box don't have 64GB memory at that time. > > Ah-hah, that's interesting info. > > Let's make the default 64GB? 64GB is infinity at that time, but it no longer near infinity today. I like very large or total memory proportional number. But I'm open. Please let me see if anyone know the disadvantage of very large value. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/