From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [PATCH v7 1/4] spinlock: A new lockref structure for lockless update of refcount Date: Fri, 30 Aug 2013 12:33:49 -0700 Message-ID: References: <1375758759-29629-1-git-send-email-Waiman.Long@hp.com> <1375758759-29629-2-git-send-email-Waiman.Long@hp.com> <1377751465.4028.20.camel@pasglop> <20130829070012.GC27322@gmail.com> <52200DAE.2020303@hp.com> <5220E56A.80603@hp.com> <5220F090.5050908@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Ingo Molnar , Benjamin Herrenschmidt , Alexander Viro , Jeff Layton , Miklos Szeredi , Ingo Molnar , Thomas Gleixner , linux-fsdevel , Linux Kernel Mailing List , Peter Zijlstra , Steven Rostedt , Andi Kleen , "Chandramouleeswaran, Aswin" , "Norton, Scott J" To: Waiman Long Return-path: Received: from mail-vc0-f174.google.com ([209.85.220.174]:62256 "EHLO mail-vc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754033Ab3H3Tdw (ORCPT ); Fri, 30 Aug 2013 15:33:52 -0400 In-Reply-To: <5220F090.5050908@hp.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, Aug 30, 2013 at 12:20 PM, Waiman Long wrote: > > Below is the perf data of my short workloads run in an 80-core DL980: Ok, that doesn't look much like d_lock any more. Sure, there's a small amount of spinlocking going on with lockref being involved, but on the whole even that looks more like getcwd and other random things. I do agree that getcwd() can probably be hugely optimized. Nobody has ever bothered, because it's never really performance-critical, and I think AIM7 ends up just doing something really odd. I bet we could fix it entirely if we cared enough. I just wonder if it's even worth it (I assume AIM7 is something HP uses internally, because I've never really heard of anybody else caring) But I'll look at getcwd anyway. Linus