Which is best for DSP applications? Is the ARM still more general purpose and hence slower or catching up? I am talking full floating point arithmetic.
32 bit ARM Cortex vs DSP Processor
Started by ●April 9, 2015
Reply by ●April 9, 20152015-04-09
On 4/9/15 4:36 AM, gyansorova@gmail.com wrote:> Which is best for DSP applications? Is the ARM still more general purpose and hence slower or catching up? I am talking full floating point arithmetic.the clock speeds for the ARM seem to be updated daily, but last i looked, the DSP chips usually ran *slower*, but they might do more per instruction than the ARM. certainly coding DSP on an ARM or other general-purpose CPU has disadvantages (like what you must to with circular addressing) as well as advantages (doing "non-DSP" stuff with a DSP can be messy) over a DSP. -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."
Reply by ●April 9, 20152015-04-09
On Thu, 09 Apr 2015 01:36:35 -0700, gyansorova wrote:> Which is best for DSP applications? Is the ARM still more general > purpose and hence slower or catching up? I am talking full floating > point arithmetic.There's lots of different ARM Cortexes out there. You talkin' M0, A8, R4 or what? What's best? Easiest to hire programmers for? Fastest? Most energy efficient? Best looking booth babes? My suspicion is that for pure blazing fast number crunching, and perhaps even FLOPS/Joule, the DSPs still have a hold on things. But I dunno. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●April 9, 20152015-04-09
On Friday, April 10, 2015 at 4:20:53 AM UTC+12, Tim Wescott wrote:> On Thu, 09 Apr 2015 01:36:35 -0700, gyansorova wrote: > > > Which is best for DSP applications? Is the ARM still more general > > purpose and hence slower or catching up? I am talking full floating > > point arithmetic. > > There's lots of different ARM Cortexes out there. You talkin' M0, A8, R4 > or what? > > What's best? Easiest to hire programmers for? Fastest? Most energy > efficient? Best looking booth babes? > > My suspicion is that for pure blazing fast number crunching, and perhaps > even FLOPS/Joule, the DSPs still have a hold on things. But I dunno. > > -- > > Tim Wescott > Wescott Design Services > http://www.wescottdesign.comThanks folks, much appreciated.
Reply by ●April 10, 20152015-04-10
On Thu, 09 Apr 2015 11:39:44 -0700, gyansorova wrote:> On Friday, April 10, 2015 at 4:20:53 AM UTC+12, Tim Wescott wrote: >> On Thu, 09 Apr 2015 01:36:35 -0700, gyansorova wrote: >> >> > Which is best for DSP applications? Is the ARM still more general >> > purpose and hence slower or catching up? I am talking full floating >> > point arithmetic. >> >> There's lots of different ARM Cortexes out there. You talkin' M0, A8, >> R4 or what? >> >> What's best? Easiest to hire programmers for? Fastest? Most energy >> efficient? Best looking booth babes? >> >> My suspicion is that for pure blazing fast number crunching, and >> perhaps even FLOPS/Joule, the DSPs still have a hold on things. But I >> dunno. >> >> -- >> >> Tim Wescott Wescott Design Services http://www.wescottdesign.com > > Thanks folks, much appreciated.Wow, I feel like I didn't deliver much value -- questions, and an "I dunno" gets me a "much appreciated"! -- www.wescottdesign.com
Reply by ●April 10, 20152015-04-10
Tim Wescott <tim@seemywebsite.com> writes:> On Thu, 09 Apr 2015 11:39:44 -0700, gyansorova wrote: > >> On Friday, April 10, 2015 at 4:20:53 AM UTC+12, Tim Wescott wrote: >>> On Thu, 09 Apr 2015 01:36:35 -0700, gyansorova wrote: >>> >>> > Which is best for DSP applications? Is the ARM still more general >>> > purpose and hence slower or catching up? I am talking full floating >>> > point arithmetic. >>> >>> There's lots of different ARM Cortexes out there. You talkin' M0, A8, >>> R4 or what? >>> >>> What's best? Easiest to hire programmers for? Fastest? Most energy >>> efficient? Best looking booth babes? >>> >>> My suspicion is that for pure blazing fast number crunching, and >>> perhaps even FLOPS/Joule, the DSPs still have a hold on things. But I >>> dunno. >>> >>> -- >>> >>> Tim Wescott Wescott Design Services http://www.wescottdesign.com >> >> Thanks folks, much appreciated. > > Wow, I feel like I didn't deliver much value -- questions, and an "I > dunno" gets me a "much appreciated"!Tim, your question "Best looking booth babes?" was much appreciated here. Metrics: love 'em / hate 'em. -- Randy Yates Digital Signal Labs http://www.digitalsignallabs.com
Reply by ●April 10, 20152015-04-10
One difference may be latency. Many DSP's can run in one sample-at-a-time mode without losing too much efficiency but ARM cores assume heavy multi-threading which requires lots of buffering. Bob
Reply by ●April 10, 20152015-04-10
On Fri, 10 Apr 2015 05:36:05 -0700, radams2000 wrote:> One difference may be latency.Definitely. One good way to distinguish a good-looking applications engineer from a mere booth babe is to see how fast they are on the uptake. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●April 11, 20152015-04-11
On 4/9/2015 10:02 AM, robert bristow-johnson wrote:> On 4/9/15 4:36 AM, gyansorova@gmail.com wrote: >> Which is best for DSP applications? Is the ARM still more general >> purpose and hence slower or catching up? I am talking full floating >> point arithmetic. > > the clock speeds for the ARM seem to be updated daily, but last i > looked, the DSP chips usually ran *slower*, but they might do more per > instruction than the ARM. certainly coding DSP on an ARM or other > general-purpose CPU has disadvantages (like what you must to with > circular addressing) as well as advantages (doing "non-DSP" stuff with a > DSP can be messy) over a DSP.Which tastes better, oranges or apples? I think your info on DSPs may or may not be out of date depending on which DSP chips and which ARMs you are comparing. There are quad core ARMs running at 1.5 GHz even if they aren't especially suited to DSP work. There are similarly clocked DSP chips with at least 8 ALUs per core and possibly two cores (I am a bit out of date with the high end). On the lower end there are ARM CM4 chips which approach 1 MAC per clock in the 70 to 100 MHz ball park to compare to lower end DSPs designed for low power apps. But the low end ARM DSP oriented devices (called DSC for Digital Signal Controllers by marketing) are strictly integer unless you take a large hit on performance. If you need floating point DSP, I think you are still better off with true DSP chips... unless your performance needs are fairly low and you have a compelling reason to use a more MCU like device. -- Rick
Reply by ●April 11, 20152015-04-11
On Saturday, April 11, 2015 at 4:55:36 PM UTC+12, rickman wrote:> On 4/9/2015 10:02 AM, robert bristow-johnson wrote: > > On 4/9/15 4:36 AM, gyansorova@gmail.com wrote: > >> Which is best for DSP applications? Is the ARM still more general > >> purpose and hence slower or catching up? I am talking full floating > >> point arithmetic. > > > > the clock speeds for the ARM seem to be updated daily, but last i > > looked, the DSP chips usually ran *slower*, but they might do more per > > instruction than the ARM. certainly coding DSP on an ARM or other > > general-purpose CPU has disadvantages (like what you must to with > > circular addressing) as well as advantages (doing "non-DSP" stuff with a > > DSP can be messy) over a DSP. > > Which tastes better, oranges or apples? > > I think your info on DSPs may or may not be out of date depending on > which DSP chips and which ARMs you are comparing. There are quad core > ARMs running at 1.5 GHz even if they aren't especially suited to DSP > work. There are similarly clocked DSP chips with at least 8 ALUs per > core and possibly two cores (I am a bit out of date with the high end). > On the lower end there are ARM CM4 chips which approach 1 MAC per > clock in the 70 to 100 MHz ball park to compare to lower end DSPs > designed for low power apps. But the low end ARM DSP oriented devices > (called DSC for Digital Signal Controllers by marketing) are strictly > integer unless you take a large hit on performance. > > If you need floating point DSP, I think you are still better off with > true DSP chips... unless your performance needs are fairly low and you > have a compelling reason to use a more MCU like device. > > -- > > RickMuch more appreciated guv - thanks.
