From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:34379 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753768AbcJER6X (ORCPT ); Wed, 5 Oct 2016 13:58:23 -0400 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u95Hrhjn011257 for ; Wed, 5 Oct 2016 13:58:22 -0400 Received: from e24smtp05.br.ibm.com (e24smtp05.br.ibm.com [32.104.18.26]) by mx0b-001b2d01.pphosted.com with ESMTP id 25w4963g9b-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 05 Oct 2016 13:58:22 -0400 Received: from localhost by e24smtp05.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 5 Oct 2016 14:58:20 -0300 Subject: Re: aio: questions with ioctx_alloc() and large num_possible_cpus() To: Benjamin LaHaise References: <20161005174146.GK23336@kvack.org> Cc: Kent Overstreet , Alexander Viro , linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-kernel@vger.kernel.org From: Mauricio Faria de Oliveira Date: Wed, 5 Oct 2016 14:58:12 -0300 MIME-Version: 1.0 In-Reply-To: <20161005174146.GK23336@kvack.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Message-Id: <737b5bf7-329e-c59d-7601-aea0f4ffbeab@linux.vnet.ibm.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Hi Benjamin, On 10/05/2016 02:41 PM, Benjamin LaHaise wrote: > I'd suggest increasing the default limit by changing how it is calculated. > The current number came about 13 years ago when machines had orders of > magnitude less RAM than they do today. Thanks for the suggestion. Does the default also have implications other than memory usage? For example, concurrency/performance of as much aio contexts running, or if userspace could try to exploit some point with a larger number? Wondering about it because it can be set based on num_possible_cpus(), but that might be really large on high-end systems. Regards, -- Mauricio Faria de Oliveira IBM Linux Technology Center