From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034760AbdAIQAn (ORCPT ); Mon, 9 Jan 2017 11:00:43 -0500 Received: from mail-io0-f179.google.com ([209.85.223.179]:35581 "EHLO mail-io0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965740AbdAIQAg (ORCPT ); Mon, 9 Jan 2017 11:00:36 -0500 MIME-Version: 1.0 In-Reply-To: <20170109102219.GF7495@dhcp22.suse.cz> References: <20170106152052.GS5556@dhcp22.suse.cz> <20170106160743.GU5556@dhcp22.suse.cz> <20170106161944.GW5556@dhcp22.suse.cz> <20170109102219.GF7495@dhcp22.suse.cz> From: Eric Dumazet Date: Mon, 9 Jan 2017 08:00:16 -0800 Message-ID: Subject: Re: __GFP_REPEAT usage in fq_alloc_node To: Michal Hocko Cc: linux-mm@kvack.org, LKML 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 Mon, Jan 9, 2017 at 2:22 AM, Michal Hocko wrote: > > the changelog doesn't mention it but this, unlike other kvmalloc > conversions is not without functional changes. The kmalloc part > will be weaker than it is with the original code for !costly (<64kB) > requests, because we are enforcing __GFP_NORETRY to break out from the > page allocator which doesn't really fail such a small requests. > > Now the question is what those code paths really prefer. Do they really > want to potentially loop in the page allocator and invoke the OOM killer > when the memory is short/fragmeted? I mean we can get into a situation > when no order-3 pages can be compacted and shooting the system down just > for that reason sounds quite dangerous to me. > > So the main question is how hard should we try before falling back to > vmalloc here? This patch is fine : 1) Default hash size is 1024 slots, 8192 bytes on 64bit arches. 2) Most of the times, qdisc are setup at boot time.