High-end AVR vs. low-end ARM?
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From: Wilco Dijkstra on 13 Nov 2008 15:42 "Ulf Samuelsson" <ulf(a)a-t-m-e-l.com> wrote in message news:gfhl33$h59$1(a)aioe.org... >> The LDRHs take 7 cycles (6 + 1), the MLAs take 6 cycles, or in total 26 cycles. >> That is exactly twice as slow as AVR32 on the above code. So the claim of 11 >> times slower is a total lie. Those Atmel marketeers should be ashamed of >> themselves. >> > > > And you are comparing 3 MACs with 6 MACs. > > 6 MACs from memory using AVR32 = 13 clocks. > 6 MACs from memory using CM3 = 52 clocks or 4 x difference. No, read again. It's 13 cycles to do 3 MACs, so 26 to do 6 MACS. Wilco
From: Wilco Dijkstra on 14 Nov 2008 06:34 "Ulf Samuelsson" <ulf(a)a-t-m-e-l.com> wrote in message news:gfhl33$h59$1(a)aioe.org... > And you are comparing 3 MACs with 6 MACs. No, read again. It's 13 cycles to do 3 MACs, so 26 to do 6 MACS. Wilco
From: Ulf Samuelsson on 14 Nov 2008 12:19 >>> The LDRHs take 7 cycles (6 + 1), the MLAs take 6 cycles, or in total 26 >>> cycles. >>> That is exactly twice as slow as AVR32 on the above code. So the claim >>> of 11 >>> times slower is a total lie. Those Atmel marketeers should be ashamed of >>> themselves. >>> >> >> >> And you are comparing 3 MACs with 6 MACs. >> >> 6 MACs from memory using AVR32 = 13 clocks. >> 6 MACs from memory using CM3 = 52 clocks or 4 x difference. > > > No, read again. It's 13 cycles to do 3 MACs, so 26 to do 6 MACS. > > Wilco > OK, I see that now, where do you check for saturation? -- Best Regards, Ulf Samuelsson This is intended to be my personal opinion which may, or may not be shared by my employer Atmel Nordic AB
From: Wilco Dijkstra on 14 Nov 2008 15:04 "Ulf Samuelsson" <ulf(a)a-t-m-e-l.com> wrote in message news:gfkcrn$7jm$1(a)aioe.org... >>>> The LDRHs take 7 cycles (6 + 1), the MLAs take 6 cycles, or in total 26 cycles. >>>> That is exactly twice as slow as AVR32 on the above code. So the claim of 11 >>>> times slower is a total lie. Those Atmel marketeers should be ashamed of >>>> themselves. >>> And you are comparing 3 MACs with 6 MACs. >>> >>> 6 MACs from memory using AVR32 = 13 clocks. >>> 6 MACs from memory using CM3 = 52 clocks or 4 x difference. >> >> >> No, read again. It's 13 cycles to do 3 MACs, so 26 to do 6 MACS. > OK, > I see that now, where do you check for saturation? There is usually no need to check for saturation unless you have 16-bit ADC's (rare). With saturation it would be 32 cycles. Wilco
From: Ulf Samuelsson on 14 Nov 2008 16:01
"Wilco Dijkstra" <Wilco.removethisDijkstra(a)ntlworld.com> skrev i meddelandet news:7RkTk.45327$nA3.22941(a)newsfe03.ams2... > > "Ulf Samuelsson" <ulf(a)a-t-m-e-l.com> wrote in message > news:gfkcrn$7jm$1(a)aioe.org... >>>>> The LDRHs take 7 cycles (6 + 1), the MLAs take 6 cycles, or in total >>>>> 26 cycles. >>>>> That is exactly twice as slow as AVR32 on the above code. So the claim >>>>> of 11 >>>>> times slower is a total lie. Those Atmel marketeers should be ashamed >>>>> of >>>>> themselves. > So the AVR32 inner loop is only 2-3 x faster than the Cortex-M3. Yes, noone in their right mind would switch for such� a meagre performance increase ;-) >>>> And you are comparing 3 MACs with 6 MACs. >>>> >>>> 6 MACs from memory using AVR32 = 13 clocks. >>>> 6 MACs from memory using CM3 = 52 clocks or 4 x difference. >>> >>> >>> No, read again. It's 13 cycles to do 3 MACs, so 26 to do 6 MACS. > >> OK, >> I see that now, where do you check for saturation? > > There is usually no need to check for saturation unless you have 16-bit > ADC's (rare). With saturation it would be 32 cycles. > > Wilco > -- Best Regards, Ulf Samuelsson This is intended to be my personal opinion which may, or may not be shared by my employer Atmel Nordic AB |