From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752651AbeEOTIG (ORCPT ); Tue, 15 May 2018 15:08:06 -0400 Received: from mail-pf0-f193.google.com ([209.85.192.193]:40050 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751859AbeEOTIE (ORCPT ); Tue, 15 May 2018 15:08:04 -0400 X-Google-Smtp-Source: AB8JxZrkp8TpVFDdaXh5UlIa7Oiy3PSxA3XuGi4BOtGsk8gLrpyHVpMLw+9QGNfw/kmDl1NVWHDakQ== Subject: Re: [PATCH V2] mlx4_core: allocate ICM memory in page size chunks To: Qing Huang , Tariq Toukan , davem@davemloft.net, haakon.bugge@oracle.com, yanjun.zhu@oracle.com Cc: netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org References: <20180511192318.22342-1-qing.huang@oracle.com> <2797ac27-022c-0818-388c-e4a6131ad1ca@gmail.com> <1ded7d49-0ba2-3594-f840-74d7cf37a0eb@mellanox.com> From: Eric Dumazet Message-ID: Date: Tue, 15 May 2018 12:08:01 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/15/2018 11:53 AM, Qing Huang wrote: > >> This is control path so it is less latency-sensitive. >> Let's not produce unnecessary degradation here, please call kvzalloc so we maintain a similar behavior when contiguous memory is available, and a fallback for resiliency. > > No sure what exactly degradation is caused by vzalloc here. I think it's better to keep physically contiguous pages > to other requests which really need them. Besides slow path/mem compacting can be really expensive. > Just use kvzalloc(), and you get the benefit of having contiguous memory if available, without expensive compact phase. This thing _automatically_ falls back to vmalloc(), thus your problem will be solved. If you are not sure, trust others.