From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f181.google.com (mail-pd0-f181.google.com [209.85.192.181]) by kanga.kvack.org (Postfix) with ESMTP id 1554B6B0035 for ; Mon, 31 Mar 2014 19:13:11 -0400 (EDT) Received: by mail-pd0-f181.google.com with SMTP id p10so8547969pdj.26 for ; Mon, 31 Mar 2014 16:13:10 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id mv8si7637524pab.92.2014.03.31.16.13.09 for ; Mon, 31 Mar 2014 16:13:10 -0700 (PDT) Date: Mon, 31 Mar 2014 16:13:08 -0700 From: Andrew Morton Subject: Re: [PATCH] ipc,shm: increase default size for shmmax Message-Id: <20140331161308.6510381345cb9a1b419d5ec0@linux-foundation.org> In-Reply-To: <1396306773.18499.22.camel@buesod1.americas.hpqcorp.net> References: <1396235199.2507.2.camel@buesod1.americas.hpqcorp.net> <20140331143217.c6ff958e1fd9944d78507418@linux-foundation.org> <1396306773.18499.22.camel@buesod1.americas.hpqcorp.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Davidlohr Bueso Cc: Manfred Spraul , aswin@hp.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Mon, 31 Mar 2014 15:59:33 -0700 Davidlohr Bueso wrote: > > > > - Shouldn't there be a way to alter this namespace's shm_ctlmax? > > Unfortunately this would also add the complexity I previously mentioned. But if the current namespace's shm_ctlmax is too small, you're screwed. Have to shut down the namespace all the way back to init_ns and start again. > > - What happens if we just nuke the limit altogether and fall back to > > the next check, which presumably is the rlimit bounds? > > afaik we only have rlimit for msgqueues. But in any case, while I like > that simplicity, it's too late. Too many workloads (specially DBs) rely > heavily on shmmax. Removing it and relying on something else would thus > cause a lot of things to break. It would permit larger shm segments - how could that break things? It would make most or all of these issues go away? First principles: why does this thing exist? What problem was SHMMAX created to solve? It doesn't appear to be part of posix: http://pubs.opengroup.org/onlinepubs/000095399/functions/shmget.html [ENOMEM] A shared memory identifier and associated shared memory segment shall be created, but the amount of available physical memory is not sufficient to fill the request. -- 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