From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: Software prefetching considered harmful Date: Fri, 20 May 2011 19:13:28 +1000 Message-ID: <1305882808.7481.163.camel@pasglop> References: <1305855769.7481.114.camel@pasglop> <20110520083442.GB22802@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from gate.crashing.org ([63.228.1.57]:46324 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935447Ab1ETJNu (ORCPT ); Fri, 20 May 2011 05:13:50 -0400 In-Reply-To: <20110520083442.GB22802@elte.hu> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Ingo Molnar Cc: Linus Torvalds , linux-arch@vger.kernel.org, David Miller , Russell King > Yeah, over the past 10 years we have been suffering from an increasing level of > blindness in the area of x86 performance analysis. Our old tools gradually > deteriorated, the hardware got smarter and more parallel and it was harder and > harder to see what happens. The 32-bit/64-bit split did not help us stay > focused either. I think i warned about this 4-5 years ago at a KS. > > This has improved meanwhile, we now have better tools (*wink* :) and have a > good performance monitoring model (*wink* :) and people are again looking at > the fine details and i think we now have a good chance to speed up the kernel > again and keep it fast - and not just on PowerPC which has its envied Olympus > of performance gods! :-) Hehe, right. I agree completely. > Watching out for performance is a fundamentally critical mass thing: for a long > time it seems a Sisyphean task with little progress, then it just happens very > quickly. I used to pay a lot more attention to performance myself than I do nowadays, and that is definitely not a good thing. Mostly blame being swamped with other things but still something I need to remedy in the near future. Cheers, Ben.