Hi Siahrhei, Thank you for your suggestion. I believe I am turning on the cache by calling:
void cpu_dcache_enable(void) { u32 reg ; reg = get_cr(); timer_delay_ms(1) ; set_cr(reg | CR_C); } void cpu_icache_enable(void) { u32 reg ; reg = get_cr(); timer_delay_ms(1) ; set_cr(reg | CR_I); } which I believe turn on/off C (CP15) bits. I installed Antutu on that hardware (melee a1000g) and managed to over-clock it to 1200Mhz and could make sure it was a real over clocking - meaning that the system indeed became faster. I guess PLL1 is not the only guy that should be dealt with - perhaps someone knows what else? I'll keep looking into this. Thanks again! On Thursday, August 28, 2014 10:13:45 AM UTC+3, Siarhei Siamashka wrote: > > On Mon, 25 Aug 2014 05:43:04 -0700 (PDT) > RFat <raa...@gmail.com <javascript:>> wrote: > > > Hi all, > > > > I am trying to overclock the A31 higher than 1008MHz > > Are you fine with the deterioration of reliability and/or overheating > under high load? > > > and I am getting deterioration in performance. > > > > The way I work is execute a small program from u-boot which redefines > the N > > multiplayer of PLL1 and then runs some CPU-intentive routine (to measure > > performance). > > > > Here are the results I get (the N multiplier is given in the small > brackets > > starting from 18): > > > > CPU Freq = 864Mhz (18) > > run in 10Hz, 94ms > > PLL1 is ENABLED P:2 M:1 K:3 N:18 Sigma:0 Lock:0 Freq:432Mhz > coreclk:864Mhz > > CPU Freq = 912Mhz (19) > > run in 11Hz, 89ms > > PLL1 is ENABLED P:2 M:1 K:3 N:19 Sigma:0 Lock:0 Freq:456Mhz > coreclk:912Mhz > > CPU Freq = 960Mhz (20) > > run in 11Hz, 85ms > > PLL1 is ENABLED P:2 M:1 K:3 N:20 Sigma:0 Lock:0 Freq:480Mhz > coreclk:960Mhz > > CPU Freq = 1008Mhz (21) > > run in 12Hz, 81ms > > PLL1 is ENABLED P:2 M:1 K:3 N:21 Sigma:0 Lock:0 Freq:504Mhz > coreclk:1008Mhz > > CPU Freq = 1056Mhz (22) > > run in 12Hz, 77ms > > PLL1 is ENABLED P:2 M:1 K:3 N:22 Sigma:0 Lock:0 Freq:528Mhz > coreclk:1056Mhz > > CPU Freq = 1104Mhz (23) > > run in 9Hz, 101ms > > PLL1 is ENABLED P:2 M:1 K:3 N:23 Sigma:0 Lock:0 Freq:552Mhz > coreclk:1104Mhz > > CPU Freq = 1152Mhz (24) > > run in 9Hz, 101ms > > PLL1 is ENABLED P:2 M:1 K:3 N:24 Sigma:0 Lock:0 Freq:576Mhz > coreclk:1152Mhz > > CPU Freq = 1200Mhz (25) > > run in 9Hz, 101ms > > PLL1 is ENABLED P:2 M:1 K:3 N:25 Sigma:0 Lock:0 Freq:600Mhz > coreclk:1200Mhz > > CPU Freq = 1248Mhz (26) > > run in 9Hz, 101ms > > PLL1 is ENABLED P:2 M:1 K:3 N:26 Sigma:0 Lock:0 Freq:624Mhz > coreclk:1248Mhz > > CPU Freq = 1296Mhz (27) > > run in 9Hz, 101ms > > PLL1 is ENABLED P:2 M:1 K:3 N:27 Sigma:0 Lock:0 Freq:648Mhz > coreclk:1296Mhz > > CPU Freq = 1344Mhz (28) > > run in 9Hz, 101ms > > PLL1 is ENABLED P:2 M:1 K:3 N:28 Sigma:0 Lock:0 Freq:672Mhz > coreclk:1344Mhz > > CPU Freq = 1392Mhz (29) > > run in 9Hz, 101ms > > PLL1 is ENABLED P:2 M:1 K:3 N:29 Sigma:0 Lock:0 Freq:696Mhz > coreclk:1392Mhz > > > > As you can see, after 1008 (or 1056) there's a _decrease_ in > performance. > > I can see that the performance flattens out and remains at the same > 101ms level for your CPU-intensive routine. > > If you are running the code in u-boot from SRAM and the L1 cache is not > enabled, then the instructions fetch may become a bottleneck. > > > Does anyone knows how higher performance can be achieved? > > Maybe buy a different higher performance SoC or better optimize the > software? > > -- > Best regards, > Siarhei Siamashka > -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.