From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: Software prefetching considered harmful Date: Thu, 19 May 2011 12:38:40 -0700 Message-ID: References: <20110519.153259.1670240855485459381.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:44976 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934417Ab1ESTjc (ORCPT ); Thu, 19 May 2011 15:39:32 -0400 Received: from mail-ew0-f46.google.com (mail-ew0-f46.google.com [209.85.215.46]) (authenticated bits=0) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id p4JJd2Fg027932 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=FAIL) for ; Thu, 19 May 2011 12:39:03 -0700 Received: by ewy4 with SMTP id 4so965186ewy.19 for ; Thu, 19 May 2011 12:39:00 -0700 (PDT) In-Reply-To: <20110519.153259.1670240855485459381.davem@davemloft.net> Sender: linux-arch-owner@vger.kernel.org List-ID: To: David Miller Cc: linux-arch@vger.kernel.org, mingo@elte.hu, benh@kernel.crashing.org, rmk@arm.linux.org.uk On Thu, May 19, 2011 at 12:32 PM, David Miller wrote: > > It's been my experience that prefetch hurts more than it ever helps > for these list traversal functions. > > In fact I had been looking at some assembler output for files in the > networking and noticed how all of these list prefetch turds just take > up I-cache space. > > Please kill them off, you have my utmost support :-) Hmm. Networking tends to use both hlist and regular lists. Does it go for both for you, or is one or the other more of an issue? Lius