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by HPCguy
Tue Jan 12, 2021 12:58 pm
Forum: Advanced users
Topic: Predictable Linux cache-friendly memory performance/behavior/allocation
Replies: 8
Views: 524

Re: Predictable Linux cache-friendly memory performance/behavior/allocation

Hi, https://elixir.bootlin.com/linux/latest ... dma-heap.h Debian packaged headers will lag the latest, but that has been in our kernel branch since 5.4. That doesn't seem to be in PiOS 32, just yet. I will keep looking. I am trying to reduce latency for both cache misses and TLB misses, for well ma...
by HPCguy
Tue Jan 12, 2021 12:39 pm
Forum: Advanced users
Topic: Does anyone know where to find the 8GB = D9ZCL = MT53E2G32D4NQ-046 WT:A data sheet?
Replies: 1
Views: 84

Does anyone know where to find the 8GB = D9ZCL = MT53E2G32D4NQ-046 WT:A data sheet?

Does anyone know where to find the 8GB = D9ZCL = MT53E2G32D4NQ-046 WT:A data sheet?

I'd like to know how this memory chip is arranged internally, so I can potentially try to implement PALLOC for better L2 cache isolation between cores.

https://github.com/heechul/palloc
by HPCguy
Mon Jan 11, 2021 12:07 pm
Forum: General discussion
Topic: fastest pi possible
Replies: 41
Views: 1254

Re: fastest pi possible

My advice would be to use the 4GB Pi 4, clock it down, shut off as much I/O as possible (e.g. disable bluetooth, etc.) and configure your software to run completely out of tmpfs and never hit the SD card or USB except at boot time and shutdown.
by HPCguy
Mon Jan 11, 2021 11:12 am
Forum: Advanced users
Topic: Predictable Linux cache-friendly memory performance/behavior/allocation
Replies: 8
Views: 524

Re: Predictable Linux cache-friendly memory performance/behavior/allocation

@6by9 Thanks for the info. I can't find the ioctl() option DMA_HEAP_IOCTL_ALLOC in the include directories, or anything like it. I thought that even Kernel CMA was limited to the lowest 1GB on the PI. I will dig deeper now that you've posted this. Maybe vfio can give me contiguous physical pages wit...
by HPCguy
Thu Dec 31, 2020 8:13 am
Forum: Advanced users
Topic: Predictable Linux cache-friendly memory performance/behavior/allocation
Replies: 8
Views: 524

Re: Predictable Linux cache-friendly memory performance/behavior/allocation

The code above already used mlock. What I found is that the algorithm above has to do at least a couple of allocations to get a "cache friendly" mapping as I defined that term in the text above. In fact, I found that when using a simple posix_memalign, the first attempt is *almost always* ...
by HPCguy
Sat Dec 26, 2020 1:38 pm
Forum: Advanced users
Topic: Predictable Linux cache-friendly memory performance/behavior/allocation
Replies: 8
Views: 524

Predictable Linux cache-friendly memory performance/behavior/allocation

Hi, I am trying to get predictable code performance on the Raspberry Pi, and that requires predictable memory mapping. To that end, I wrote a "cache friendly" pinned memory allocator for my Pi 4. Here is the code for anyone looking for such a thing: /* This program creates a pinned cache-f...
by HPCguy
Mon Oct 26, 2020 11:22 am
Forum: Bare metal, Assembly language
Topic: Experience with RPi 4 Translation Control Register TBI bits?
Replies: 3
Views: 365

Re: Experience with RPi 4 Translation Control Register TBI bits?

It seems like an ASM statement as simple as the following might work if it could be executed at the right privilege level: asm volatile("mrs r12, TCR_EL1\n\t" "ldr r11, #0x0000002000000000\n\t" "orr r12, r12, r11\n\t" "msr TCR_EL1, r12\n\t" ::: "r11"...
by HPCguy
Mon Oct 26, 2020 9:22 am
Forum: Bare metal, Assembly language
Topic: Experience with RPi 4 Translation Control Register TBI bits?
Replies: 3
Views: 365

Re: Experience with RPi 4 Translation Control Register TBI bits?

@LdB: Thanks. Do you know the mechanics of how/where I would go about properly configuring the TBI bits in TCR registers without breaking anything? I'm assuming I need to be running in Exception Level 1 to do anything? The following link is the only place I saw any information on this topic, and a s...
by HPCguy
Mon Oct 26, 2020 1:54 am
Forum: General discussion
Topic: Pi 4 usb-boot questions for RonR
Replies: 3
Views: 321

Re: Pi 4 usb-boot questions for RonR

Thanks! This is exactly the information I needed. I'll give it a shot later tonight.
by HPCguy
Sun Oct 25, 2020 11:21 am
Forum: General discussion
Topic: Pi 4 usb-boot questions for RonR
Replies: 3
Views: 321

Pi 4 usb-boot questions for RonR

Hi, I looked at the usb-boot.txt file and code included in RonR's usb-boot.zip archive, and I came away a bit unsure of exactly what usb-boot will be doing when I run it. Background: I am brand new to the Raspberry Pi environment. I received an SD card with my Pi model 4B that has Noobs on it. I ran...
by HPCguy
Sun Oct 25, 2020 7:44 am
Forum: Beginners
Topic: Which performance for a USB flash drive?
Replies: 7
Views: 281

Re: Which performance for a USB flash drive?

https://www.youtube.com/watch?v=lxuKqBYvDQs

Look at two minutes 30 seconds into the video.
by HPCguy
Sun Oct 25, 2020 7:31 am
Forum: Beginners
Topic: Suggested area of Raspberry Engineering
Replies: 5
Views: 299

Re: Suggested area of Raspberry Engineering

I used a hand drill to put more holes in my case. Worked great!
by HPCguy
Sun Oct 25, 2020 6:02 am
Forum: Bare metal, Assembly language
Topic: Experience with RPi 4 Translation Control Register TBI bits?
Replies: 3
Views: 365

Experience with RPi 4 Translation Control Register TBI bits?

Hi, I have a Raspberry Pi Model 4. Has anyone played with the TCR_EL1 - TCR_EL3 TBI bits? I would like to embed a pointer increment in the upper "unused" bits of the virtual address space of a 64-bit pointer when running in AArch64 mode. Apparently, I can do this without page faulting if I...
by HPCguy
Mon Oct 19, 2020 8:13 am
Forum: Beginners
Topic: Maximizing the lifetime of an SD card
Replies: 22
Views: 928

Re: Maximizing the lifetime of an SD card

I'm a developer. I'm constantly compiling huge programs and pulling down large documents and datasets from the web, then discarding them before the day is over. Originally, SD cards were introduced to the mass markets in items like cameras, where whatever was written to the card was largely static, ...
by HPCguy
Sun Oct 18, 2020 1:35 am
Forum: General discussion
Topic: ETA for reliable USB flash drive imager?
Replies: 57
Views: 1761

Re: ETA for reliable USB flash drive imager?

@bjtheone: But isn't the root of your issue NOOBs which behaves differently than what has become the "standard" install method Yes, that was the first part of my problem. But I also tried to install retropie (RPI 4) to a USB drive with rpi-imager for my model 4B, and got similar boot loade...
by HPCguy
Sun Oct 18, 2020 12:58 am
Forum: General discussion
Topic: Walkthrough script for creating model 4B USB drives
Replies: 6
Views: 308

Re: Walkthrough script for creating model 4B USB drives

Yeah, I'm not sure why you got a different result from me for that awk generated date. At any rate, I switched the technique as noted in my posts above, thanks to you. The new code is better, anyway.
by HPCguy
Sun Oct 18, 2020 12:55 am
Forum: Beginners
Topic: Maximizing the lifetime of an SD card
Replies: 22
Views: 928

Re: Maximizing the lifetime of an SD card

That's the way to do it!

My assumption is that a lot of users, especially educational users, never use anything other than an SD card, which is why I think this is an important topic for a MagPi issue.
by HPCguy
Sun Oct 18, 2020 12:45 am
Forum: General discussion
Topic: Walkthrough script for creating model 4B USB drives
Replies: 6
Views: 308

Re: Walkthrough script for creating model 4B USB drives

Thanks again, Ron I switched the date collection to the following, which also let me get rid of the check for sudo: $ `vcgencmd bootloader_version | head -n 1` I edited the script posted at the following link to reflect all fixes: https://www.raspberrypi.org/forums/viewtopic.php?f=91&t=288366&am...
by HPCguy
Sat Oct 17, 2020 11:43 pm
Forum: General discussion
Topic: Walkthrough script for creating model 4B USB drives
Replies: 6
Views: 308

Re: Walkthrough script for creating model 4B USB drives

Thanks Ron. The eche was a problem that snuck in and I did edit the code I had posted on the forum to fix that. Did you leave the #!/bin/bash at the top? The rest is working fine for me, so I can't really debug it... I just copy/pasted the code back from the forum to a file named xxx on my own devic...
by HPCguy
Sat Oct 17, 2020 2:06 pm
Forum: Beginners
Topic: Maximizing the lifetime of an SD card
Replies: 22
Views: 928

Re: Maximizing the lifetime of an SD card

That's why I turned it off. It didnt make sense to me.
by HPCguy
Sat Oct 17, 2020 1:10 pm
Forum: Beginners
Topic: USB boot device
Replies: 11
Views: 680

Re: USB boot device

So then why haven't the boot rom version, or at least the USB boot order option already been deprecated out of raspi-config?
by HPCguy
Sat Oct 17, 2020 11:19 am
Forum: General discussion
Topic: Walkthrough script for creating model 4B USB drives
Replies: 6
Views: 308

Walkthrough script for creating model 4B USB drives

Hi, I just created a script that guides people through the process of creating a USB drive on the model 4B. I had a lot of frustration when I tried it, and wished I would l have had help. Hopefully the script will help some of you avoid the pain I went through. The script just tells people what to d...
by HPCguy
Sat Oct 17, 2020 11:01 am
Forum: Beginners
Topic: USB boot device
Replies: 11
Views: 680

Re: USB boot device

I've created a script that will walk people through the steps they need to take to create a USB drive for the Raspberry Pi Model 4B. These are the steps I went through. This doesn't modify anything, it just guides you through the process. Hopefully some people will find it useful. I called it USB-im...
by HPCguy
Sat Oct 17, 2020 6:01 am
Forum: Beginners
Topic: USB boot device
Replies: 11
Views: 680

Re: USB boot device

I just went through some problems with this. My advice is to only use the rpi-imager program and only select the 32 bit raspberry pi OS option of the rpi-imager program. That seemed to be the most reliable way to get me past my problems. That configuration provides a good sanity check to know if you...
by HPCguy
Sat Oct 17, 2020 5:51 am
Forum: Bare metal, Assembly language
Topic: Assembler sections
Replies: 15
Views: 819

Re: Assembler sections

My fault. I meant your solution for getting past the Segfault, when you find it.

Thanks.

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