From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: another pmem variant V2 Date: Thu, 2 Apr 2015 18:41:39 +0200 Message-ID: <20150402164139.GA9774@lst.de> References: <1427358764-6126-1-git-send-email-hch@lst.de> <94D0CD8314A33A4D9D801C0FE68B40295A853392@G9W0745.americas.hpqcorp.net> <20150401072608.GA24312@lst.de> <94D0CD8314A33A4D9D801C0FE68B40295A856737@G9W0745.americas.hpqcorp.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Christoph Hellwig , "linux-nvdimm@ml01.01.org" , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , "ross.zwisler@linux.intel.com" , "axboe@kernel.dk" , "boaz@plexistor.com" , "Kani, Toshimitsu" To: "Elliott, Robert (Server Storage)" Return-path: Content-Disposition: inline In-Reply-To: <94D0CD8314A33A4D9D801C0FE68B40295A856737@G9W0745.americas.hpqcorp.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu, Apr 02, 2015 at 03:11:36PM +0000, Elliott, Robert (Server Stora= ge) wrote: > Attr Copy Read IOPS Write IOPS > =3D=3D=3D=3D =3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D > UC memcpy 36 K 22 K > UC NT rd,wr 513 K 326 K >=20 > WB memcpy 3.4 M 2.5 M > WB NT rd,wr 3.3 M 3.5 M >=20 > WC memcpy 776 K 3.5 M > WC NT rd,wr 3.0 M 3.9 M >=20 > WT memcpy 2.1 M 22 K > WT NT rd,wr 3.3 M 2.1 M >=20 > a few other variations yielded the peak numbers: > WC NT rd only 3.2 M 4.1 M > WC NT wr only 712 K 4.6 M > WT NT wr only 2.6 M 4.0 M >=20 > There are lots of tuning considerations for those memcpy=20 > functions - how far to unroll the loop, whether to > include PRFETCHNTA instructions, etc. Looks like we should a=D1=96m for WC + NT would be a good start. Can you prepare a patch to add your NT memcpy variants and a second one to use them in the pmem driver?