From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [test result] dirty logging without srcu update -- Re: [RFC][PATCH] srcu: Implement call_srcu() Date: Thu, 02 Feb 2012 12:21:58 +0200 Message-ID: <4F2A63C6.7030301@redhat.com> References: <1328016724.2446.229.camel@twins> <4F27F0E6.1040309@redhat.com> <1328017807.2446.230.camel@twins> <20120131222447.GH2391@linux.vnet.ibm.com> <1328091749.2760.34.camel@laptop> <4F29178A.1090306@redhat.com> <4F2918D5.4050104@redhat.com> <4F291B56.30600@oss.ntt.co.jp> <4F291B92.8070402@redhat.com> <4F291E1F.3030505@oss.ntt.co.jp> <4F293D14.5030008@redhat.com> <20120202144633.1fc9b997.yoshikawa.takuya@oss.ntt.co.jp> <4F2A611E.6090005@redhat.com> <4F2A63B9.8000405@oss.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Peter Zijlstra , paulmck@linux.vnet.ibm.com, Oleg Nesterov , linux-kernel , Marcelo Tosatti , KVM list To: Takuya Yoshikawa Return-path: In-Reply-To: <4F2A63B9.8000405@oss.ntt.co.jp> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 02/02/2012 12:21 PM, Takuya Yoshikawa wrote: > (2012/02/02 19:10), Avi Kivity wrote: > >>> >>> ========================================================= >>> # of dirty pages: kvm.git (ns), with this patch (ns) >>> 1: 102,077 ns 10,105 ns >>> 2: 47,197 ns 9,395 ns >>> 4: 43,563 ns 9,938 ns >>> 8: 41,239 ns 10,618 ns >>> 16: 42,988 ns 12,299 ns >>> 32: 45,503 ns 14,298 ns >>> 64: 50,915 ns 19,895 ns >>> 128: 61,087 ns 29,260 ns >>> 256: 81,007 ns 49,023 ns >>> 512: 132,776 ns 86,670 ns >>> 1024: 939,299 ns 131,496 ns >>> 2048: 992,209 ns 250,429 ns >>> 4096: 891,809 ns 479,280 ns >>> 8192: 1,027,280 ns 906,971 ns >>> (until now pretty good) >>> >>> (ah, for every 32-bit atomic clear mask ...) >>> 16384: 1,270,972 ns 6,661,741 ns // 1 1 1 ... 1 >>> 32768: 1,581,335 ns 9,673,985 ns // ... >>> 65536: 2,161,604 ns 11,466,134 ns // ... >>> 131072: 3,253,027 ns 13,412,954 ns // ... >>> 262144: 5,663,002 ns 16,309,924 ns // 31 31 31 ... 31 >>> ========================================================= >> >> On a 64-bit host, this will be twice as fast. Or if we use cmpxchg16b, >> and there are no surprises, four times as fast. It will still be slower >> than the original, but by a smaller margin. > > Yes. > > I used "unsigned int" just because I wanted to use the current > atomic_clear_mask() as is. > > We need to implement atomic_clear_mask_long() or use ... If we use cmpxchg8b/cmpxchg16b then this won't fit with the atomic_*_long family. -- error compiling committee.c: too many arguments to function