From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sujit K M Subject: =?windows-1252?Q?Re=3A_MD_performance_options=3A_More_CPU=92s_or_more_Hz?= =?windows-1252?Q?=92s=3F?= Date: Wed, 4 Nov 2009 17:38:43 +0530 Message-ID: <921ca19c0911040408k6392b596t5f28cbf043e6d2c0@mail.gmail.com> References: <66781b10911040149q165edf1s94a86f179f9af9fc@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <66781b10911040149q165edf1s94a86f179f9af9fc@mail.gmail.com> Sender: linux-raid-owner@vger.kernel.org To: mark delfman Cc: Linux RAID Mailing List List-Id: linux-raid.ids I think this will be deeply involved to the RAID(Hardware) than the CPU= /Cores. =46or example if you have an RAID0 at 1.5GBsec and an RAID6 At 700MBsec= (as you have said) on Dual Core and Quad Core. I think There will be no per= formance gains with RAID0 or RAID6 on the software side. But if you use an RAID = of Higher Capacity it will be much more improved. I think it is very difficult to think in terms of RAID alone I think this is much more involved with Architectures like =46ibre Channel, IP SAN etc. On Wed, Nov 4, 2009 at 3:19 PM, mark delfman wrote: > Hi... I am wondering if anyone can offer some advice on MD performanc= e > related to CPU (speed and or cores). =A0The basic question (probably = too > basic) is =93for more MD performance are you better with more cpu=92s= or a > faster single cpu=94. =A0(in an ideal world we would have lots of ver= y > fast CPUs, but given we never have enough money....). > > Is there any grounding to the following logic: > > Presuming that a RAID0 will deliver 1.5GBsec and a RAID6 circa > 700MBsec, I am guessing there are many complex reasons for the > difference, but one of the more obvious being the need for the CPU to > perform all the necessary R6 overheads. > > If we look at a single RAID 6 configuration, then I am guessing if we > increase the speed of the CPU from eg 2.0GHz to 2.8GHz (quad core > xeon) then the RAID6 calculations would be faster? =A0Would other > overheads also be faster and if so is there any know relationship > between CPU Hz and MD performance (maybe even rough rule of thumb eg > double cpu Hz and increase R6 performance by 20% etc) > > If however I start to think of multiple RAID6 configurations maybe vi= a > iSCSI etc... then I wonder if MD would be better served with more CPU= s > instead... for example 2 x Quad core 2.0GHz xeons instead of 1 x 2.8. > =A0This theory is dependent on linux / md effectively parallel > processing the overheads and I have no knowledge in this area... henc= e > the question. > > Any thoughts anyone? > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =A0http://vger.kernel.org/majordomo-info.html > --=20 -- Sujit K M blog(http://kmsujit.blogspot.com/) -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html