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Turbo overclock
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Turbo overclock
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2nd Mar, 2014, 03:44 AM
Post: #1
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Turbo overclock
About six weeks ago a change in xbian stopped turbo overclock from working.
I recently tried setting it on the xbmc menu to see if this had been fixed, and the result was an overclock similar to 'xbian' but with 6 overvolt-very strange! After a reboot Xbian read this as 'custom' on the menus, and the system booted and ran fine. Earlier today I went through the xbmc menu again to see if I could successfully set it to 'turbo' overclock, the result was a system freeze on boot, just before the message 'mounted /'. Is there any fix for turbo overclock settings in the pipeline? |
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2nd Mar, 2014, 05:10 AM
Post: #2
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RE: Turbo overclock
I wasn't aware of a problem with Turbo OC.
I'll need to know what release you are on, output form dmesg and /boot/config.txt Turbo OC is set as Arm 1000 Core 500 SDram 500 OV +6v Have you tried setting those values in /boot/config.txt? Is there any reason you need Turbo? I'm running RC1 on no OC with no problems, even with DTS 6.1 movies. Please read before you post How to post a log file If you liked my help, click on "Thanks" to show your appreciation.
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2nd Mar, 2014, 07:09 AM
Post: #3
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Re: Turbo overclock
There's a few posts about it in the beta 2 thread, and mk01 mentioned it was something to do with a firmware change. I don't know exactly how the firmware is affecting it.
I want to use Turbo because I can..or could! It really does make a difference, and when running from USB the stability is great; who wouldn't want their pi to be sensibly controlling it's cpu for the most power possible? Setting the values you mentioned in the config.txt results in the same issue - I assumed that to set turbo is more than just setting the overclock and overvolt, since it's a firmware feature of the pi itself, with temperature management etc. I'm running rc1, without any packages from dev or staging. Here's a dmesg from a successful boot - I don't know how to get a dmesg from the unsuccessful boot, there's no ssh access. Code: [ 0.000000] Switching to timer-based delay loopThis is what currently works: Terminal root@xbian:~# cat /boot/config.txt initramfs initramfs.gz 0x00a00000 gpu_mem_512=256 gpu_mem_256=100 initial_turbo=0 decode_MPG2=0x******** decode_WVC1=0x******** hdmi_ignore_cec_init=1 hdmi_ignore_cec=1 emmc_pll_core=0 arm_freq=840 core_freq=450 sdram_freq=450 over_voltage=0 This config & cmdline example does not boot: Terminal root@xbian:~# cat /boot/config.txt initramfs initramfs.gz 0x00a00000 gpu_mem_512=256 gpu_mem_256=100 initial_turbo=0 decode_MPG2=0x******** decode_WVC1=0x******** hdmi_ignore_cec_init=1 hdmi_ignore_cec=1 emmc_pll_core=0 arm_freq=1000 core_freq=500 sdram_freq=500 over_voltage=6 root@xbian:~# cat /boot/cmdline.txt telnet zswap.enabled=1 zswap.compressor=lz4 sdhci-bcm2708.sync_after_dma=0 dwc_otg.lpm_enable=0 console=tty1 root=/dev/sda1 rootflags=subvol=root/@,thread_pool=2,autodefrag,compress=lzo,commit=5 rootfstype=btrfs rootwait smsc95xx.turbo_mode=Y elevator=cfq logo.nologo quiet noswap loglevel=0 mod_scsi.scan=sync partswap startevent=mountall nosplash nohdparm --startup-event mountall |
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2nd Mar, 2014, 09:42 AM
Post: #4
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RE: Turbo overclock
overvolt=6 is normal voltage +(6 * 0,125v) and not overclocking to 6v. Then the 5v power supply wouldn't be sufficient as well
pilight - modular domotica solution
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2nd Mar, 2014, 10:23 AM
Post: #5
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RE: Turbo overclock
Good point, made edit!
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16th Mar, 2014, 01:00 PM
Post: #6
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RE: Turbo overclock
@min
emmc_pll_core=0 is good in /boot/config.txt, xbian-package-firmware 1.4.13-1 and latest kernel package 1.3-6.10 should restore the internal workings back as it was for months before RPI's Octobers updates to kernel & firmware. for myself it is "true" as I can run again my top 950,450,500,2 . (I was never able to run turbo). If it doesn't work for you now, ... unfortunately I don't have other solution to try as above - or downgrade xbian-package-firmware below 1.4.7 and remove emmc_pll_core from config.txt. this would make your XBian the same as two/three months ago when 1.4.8 or higher of FW was posted to stable and we got reports about overclock affected. this is one dimension of the story. second one is different approach on how XBian and Raspbian handles the clocks. Raspbian turbo (1000,500,500) means you get 1000,500 (cpu/core) if system is topped to max going down to base (700,250) . Normally this sounds logically. But going to details it introduces quite significant lags & latencies for clk transitions. There we speak of microseconds what is quite significant impact. I will demonstrate: Raspbian official test on Turbo calculate 78497 prime numbers in 3m29s. my Xbian with 950,450,500 in 0:03:20.846995. For user interactive apps & actions the steppings are even with worse impact. running 1000/500 has even bad implications on clock syncs between busses. if busses are not running the same or whole number multiplication of base clock, the faster clock needs to put wait cycles. imagine two busses running 100 and 150mhz. they can speak to each other only each third cycle for 100mhz and each second for 150mhz bus. and compare this to 100 / 160 setup. it will take 4 waste cycles on 160mhz bus to speak to 100mhz bus. and if those busses are transferring data between cpu / memory / mmc ? 100/150 will be faster than 100/160 with one cycle out of four. so 25% faster. I don't remember now exactly the ratios for 1000/500 (they can be found on RPI forums) but I was always wondering why this setup. Probably the real-world use is running it at 700/250 anyhow so the drawbacks are not so visible  I know that this info will not make your RPI be running Turbo again. And yes, I know that running core at 250 and 500(or mine 450) is hell a difference ! RPI actually start working You can keep us in loop in case you will manage some other testing. Please read rules and do a search before you post! . FAQs . How to post log file? . Looking for answers? Please start here |
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29th Mar, 2014, 04:57 AM
Post: #7
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RE: Turbo overclock
thanks for the detailed explanation mk01, I actually didn't realise that the lower overclocks were also 'intelligent' in their temp & cpu scaling..oops
 I've set it to High now and there's a definite improvement! |
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3rd Apr, 2014, 02:48 PM
Post: #8
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RE: Turbo overclock
@min
I was experimenting a bit and forgot to put "emmc_pll_core=0" back. to my surprise RPI running OC without issues for maybe longer than 2 weeks (don't remember exactly when I was experimenting) (just for info refresh - we put emmc=0 stuff into config.txt to revert FW&Kernel upstream changes causing troubles (back in Oct/Nov last year)). So maybe you could try commenting it out together with your old Turbo setting (just please be sure you run xbian-package-kernel at least 1.3-6.11 and xbian-package-firmware 1.4.14). Please read rules and do a search before you post! . FAQs . How to post log file? . Looking for answers? Please start here |
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