Martin Leitner-Ankerl martinus
😎
theStack
/ arm_32bit_qemu.txt
Last active
November 22, 2023 15:15
Running Bitcoin Core on an emulated 32-bit ARM system using qemu
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| # Running Bitcoin Core on an emulated 32-bit ARM system using qemu (for reproducing issue #28906 and testing the fix PR #28913) | |
| # guide based on https://translatedcode.wordpress.com/2016/11/03/installing-debian-on-qemus-32-bit-arm-virt-board/ | |
| # tested on Ubuntu 22.04 LTS | |
| $ sudo apt-get install qemu-system-arm libguestfs-tools | |
| $ wget -O installer-vmlinuz http://http.us.debian.org/debian/dists/bookworm/main/installer-armhf/current/images/netboot/vmlinuz | |
| $ wget -O installer-initrd.gz http://http.us.debian.org/debian/dists/bookworm/main/installer-armhf/current/images/netboot/initrd.gz | |
| $ qemu-img create -f qcow2 myarmdisk.qcow2 80G | |
| $ qemu-system-arm -M virt -m 2048 -kernel installer-vmlinuz -initrd installer-initrd.gz \ | |
| -drive if=none,file=myarmdisk.qcow2,format=qcow2,id=hd \ |
imneme
/ randutils.hpp
Last active
September 25, 2024 13:41
Addresses common issues with C++11 random number generation; makes good seeding easier, and makes using RNGs easy while retaining all the power.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| /* | |
| * Random-Number Utilities (randutil) | |
| * Addresses common issues with C++11 random number generation. | |
| * Makes good seeding easier, and makes using RNGs easy while retaining | |
| * all the power. | |
| * | |
| * The MIT License (MIT) | |
| * | |
| * Copyright (c) 2015-2022 Melissa E. O'Neill | |
| * |
jboner
/ latency.txt
Last active
December 21, 2024 05:15
Latency Numbers Every Programmer Should Know
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Latency Comparison Numbers (~2012) | |
| ---------------------------------- | |
| L1 cache reference 0.5 ns | |
| Branch mispredict 5 ns | |
| L2 cache reference 7 ns 14x L1 cache | |
| Mutex lock/unlock 25 ns | |
| Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
| Compress 1K bytes with Zippy 3,000 ns 3 us | |
| Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
| Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |