From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752666Ab0BPK7P (ORCPT ); Tue, 16 Feb 2010 05:59:15 -0500 Received: from mail-ew0-f219.google.com ([209.85.219.219]:43384 "EHLO mail-ew0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750938Ab0BPK7N (ORCPT ); Tue, 16 Feb 2010 05:59:13 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:subject :content-type:content-transfer-encoding; b=Z1wR222pHIt5qTKaZxhn8HTEfZfk73tfSeW+i4fqePKQLuqlILhHlP44K6pcZIyfp3 fjzKxqbUJq3YVQ2Dz3K3NOOoux0PKspsnaYFysjcX8v4xHkavBRSzFl+dFm/ZCA5PVqb 99gaoWgzhmltHC3wF72OSY3n8+2lSVhLXZ5qM= Message-ID: <4B7A7A7A.1000805@gmail.com> Date: Tue, 16 Feb 2010 11:59:06 +0100 From: Troels Arvin User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc12 Thunderbird/3.0.1 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: msgmnb limits? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On a server with lots of RAM (192GB), I ran into an application (DB2) which applies the following sysctl changes when it's started, if the values haven't already been set to - at least - the stated values: - kernel.msgmax = 65535 - kernel.msgmnb = 65536 However, that doesn't work: Certain operations (LOAD and backups/restores) will fail with the following messages, unless kernel.msgmnb is increased: DIA8557C No message was sent using the message queue. CALLED : OS, -, msgsnd OSERR: EAGAIN (11) DATA #1 : system V message queue identifier., PD_TYPE_SYSV_QUEUE_ID I tried setting kernel.msgmnb to 524288, and then things work. This value was chosen out of the blue, and I'd like to make a more informed choice: - Is there a limit to the size of msgmnb? - Can I expect the system to start thrashing if msgmnb is increased beyond a certain value? - Is my understanding correkt: msgmnb should always be at least as large as msgmax? Thanks in advance. -- Regards, Troels Arvin