From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qa0-f49.google.com (mail-qa0-f49.google.com [209.85.216.49]) by kanga.kvack.org (Postfix) with ESMTP id 49F656B0032 for ; Thu, 11 Dec 2014 11:51:13 -0500 (EST) Received: by mail-qa0-f49.google.com with SMTP id s7so3820341qap.36 for ; Thu, 11 Dec 2014 08:51:13 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id u93si1841093qge.73.2014.12.11.08.51.11 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 11 Dec 2014 08:51:11 -0800 (PST) Date: Thu, 11 Dec 2014 17:50:58 +0100 From: Jesper Dangaard Brouer Subject: Re: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1 Message-ID: <20141211175058.64a1c2fc@redhat.com> In-Reply-To: References: <20141210163017.092096069@linux.com> <20141211143518.02c781ee@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: akpm@linuxfoundation.org, rostedt@goodmis.org, linux-kernel@vger.kernel.org, Thomas Gleixner , linux-mm@kvack.org, penberg@kernel.org, iamjoonsoo.kim@lge.com, brouer@redhat.com On Thu, 11 Dec 2014 09:03:24 -0600 (CST) Christoph Lameter wrote: > On Thu, 11 Dec 2014, Jesper Dangaard Brouer wrote: > > > It looks like an impressive saving 116 -> 60 cycles. I just don't see > > the same kind of improvements with my similar tests[1][2]. > > This is particularly for a CONFIG_PREEMPT kernel. There will be no effect > on !CONFIG_PREEMPT I hope. > > > I do see the improvement, but it is not as high as I would have expected. > > Do you have CONFIG_PREEMPT set? Yes. $ grep CONFIG_PREEMPT .config CONFIG_PREEMPT_RCU=y CONFIG_PREEMPT_NOTIFIERS=y # CONFIG_PREEMPT_NONE is not set # CONFIG_PREEMPT_VOLUNTARY is not set CONFIG_PREEMPT=y CONFIG_PREEMPT_COUNT=y Full config here: http://people.netfilter.org/hawk/kconfig/config01-slub-fastpath01 I was expecting to see at least (specifically) 4.291 ns improvement, as this is the measured[1] cost of preempt_{disable,enable] on my system. [1] https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/lib/time_bench_sample.c -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer -- 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