From mboxrd@z Thu Jan 1 00:00:00 1970 From: Luke Gorrie Subject: Re: [PATCH 0/4] DPDK memcpy optimization Date: Thu, 22 Jan 2015 10:06:19 +0100 Message-ID: References: <20150119130221.GB21790@hmsreliant.think-freely.org> <20150120151118.GD18449@hmsreliant.think-freely.org> <20150120161453.GA5316@bricha3-MOBL3> <54BF9D59.7070104@bisdn.de> <20150121130234.GB10756@bricha3-MOBL3> <54BFA7D5.7020106@bisdn.de> <20150121132620.GC10756@bricha3-MOBL3> <20150121114947.0753ae87@urahara> <20150121205404.GB32617@hmsreliant.think-freely.org> <53D2253B-DE20-486E-ADF0-DA02AAB1EF35@netgate.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: "dev-VfR2kkLFssw@public.gmane.org" To: Jim Thompson Return-path: In-Reply-To: <53D2253B-DE20-486E-ADF0-DA02AAB1EF35-jiyf0hk6h8BBDgjK7y7TUQ@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" Howdy! This memcpy discussion is absolutely fascinating. Glad to be a fly on the wall! On 21 January 2015 at 22:25, Jim Thompson wrote: > > The differences with DPDK are that a) entire cores (including the AVX/SSE > units and even AES-NI (FPU) are dedicated to DPDK, and b) DPDK is a libra= ry, > and the resulting networking applications are exactly that, applications. > The "operating system=E2=80=9D is now a control plane. > > Here is another thought: when is it time to start thinking of packet copy as a cheap unit-time operation? Packets are shrinking exponentially when measured in: - Cache lines - Cache load/store operations needed to copy - Number of vector move instructions needed to copy because those units are all based on exponentially growing quantities, while the byte size of packets stays the same for many applications. So when is it time to stop caring? (Are we already there, even, for certain conditions? How about Haswell CPU, data already exclusively in our L1 cache, start and end both known to be cache-line-aligned?) Cheers, -Luke (eagerly awaiting arrival of Haswell server...)