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ESP32-CAM Getting Started Guide
The ESP32 Camera Module is very demanded product in our Shop section. The ESP32-CAM-MB module is a small camera module with a size of 39.8mm x 27mm. This module can work independently, just connecting the USB cable. Here is a quick guide to get started and playing with this development board. 1. Connect the Camera … Read more “ESP32-CAM Getting Started Guide”
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ESP32 firmware reflash
On this article we’ll walk through the process of re-flashing the firmware of an ESP32. For this task we’ll use the online ESP Serial Flasher Tool. 1. Open the ESP Serial Flasher Tool in Chrome browser Open the following URL in your Chrome Browser: https://espressif.github.io/esptool-js 2. Set the speed to 115200. Connect your board to … Read more “ESP32 firmware reflash”
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Linux Kernel Tuning: page allocation failure
If you start seeing these errors it means your server or instance started running out of kernel memory. [10223.291166] java: page allocation failure: order:0, mode:0x1080020(GFP_ATOMIC), nodemask=(null) [10223.301794] java cpuset=/ mems_allowed=0-1 [10223.307211] CPU: 29 PID: 19395 Comm: java Not tainted 4.14.154-99.181.amzn1.x86_64 #1 [10223.315658] Hardware name: Xen HVM domU, BIOS 4.2.amazon 08/24/2006 [10223.322004] Call Trace: [10223.325230] … Read more “Linux Kernel Tuning: page allocation failure”
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AWS EBS Storage Performance Notes – Instance throughput vs Volume throughput
I just wanted to write a couple lines/guidance on this regard as this is a recurring question when configuring storage, not only in the cloud, but can also happen on bare metal servers. What is throughput on a volume? Throughput is the measure of the amount of data transferred from/to a storage device per time … Read more “AWS EBS Storage Performance Notes – Instance throughput vs Volume throughput”
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Linux Kernel Tuning: failed to alloc buffer for rx queue
If we put enough pressure over the ENA network driver, we’ll start seeing these “failed to alloc buffer for rx queue” messages on the ‘dmesg‘ output. This message will raise when the napi handler fails to refill new Rx descriptors, typically due to lack of memory. This situation might lead to performance decrease, given that … Read more “Linux Kernel Tuning: failed to alloc buffer for rx queue”
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Linux Kernel Tuning: task blocked for more than 120 seconds
This might be old school, and maybe even boring reading. But, if you concern about performance on Linux servers, at some point, you will have to have a look to the kernel messages. The problem: When we run very stressful jobs running on large servers (large number of CPU’s and RAM memory), where IO activity … Read more “Linux Kernel Tuning: task blocked for more than 120 seconds”
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