From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f71.google.com (mail-it0-f71.google.com [209.85.214.71]) by kanga.kvack.org (Postfix) with ESMTP id 7CA766B0069 for ; Fri, 6 Jan 2017 11:50:33 -0500 (EST) Received: by mail-it0-f71.google.com with SMTP id p189so23410082itg.2 for ; Fri, 06 Jan 2017 08:50:33 -0800 (PST) Received: from mail-io0-x22c.google.com (mail-io0-x22c.google.com. [2607:f8b0:4001:c06::22c]) by mx.google.com with ESMTPS id p20si2639646itc.10.2017.01.06.08.50.32 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 06 Jan 2017 08:50:32 -0800 (PST) Received: by mail-io0-x22c.google.com with SMTP id v96so36471726ioi.0 for ; Fri, 06 Jan 2017 08:50:32 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <20170106152052.GS5556@dhcp22.suse.cz> <20901069-5eb7-f5ff-0641-078635544531@suse.cz> From: Eric Dumazet Date: Fri, 6 Jan 2017 08:50:31 -0800 Message-ID: Subject: Re: __GFP_REPEAT usage in fq_alloc_node Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Michal Hocko , linux-mm@kvack.org, LKML On Fri, Jan 6, 2017 at 8:48 AM, Eric Dumazet wrote: > On Fri, Jan 6, 2017 at 8:31 AM, Vlastimil Babka wrote: > >> >> I wonder what's that cause of the penalty (when accessing the vmapped >> area I suppose?) Is it higher risk of collisions cache misses within the >> area, compared to consecutive physical adresses? > > I believe tests were done with 48 fq qdisc, each having 2^16 slots. > So I had 48 blocs,of 524288 bytes. > > Trying a bit harder at setup time to get 128 consecutive pages got > less TLB pressure. Forgot to mention tests include DDOS, so hitting a random hash bucket for every packet. -- 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