mironovdm

This tool can read current or change default HCI_LE_AUTOCONN_TIMEOUT value for Bluetooth adapter on Linux. The default value is defined for the kernel 5.15 at include/net/bluetooth/hci.h:

#define HCI_LE_AUTOCONN_TIMEOUT	msecs_to_jiffies(4000)	/* 4 seconds */

and it can be too low if the advertising interval for a device is high (for power saving).

You can also change the value in /etc/bluetooth/main.conf, line LEAutoconnecttimeout. The value in ms and will be applied at boot or when bluetooth service is restarted.

The tool changes timeout to hardcoded value 16000ms. You can change value NEW_LE_AUTOCONN_TIMEOUT in the lower source file to required value .

abel0b

apt install flex bison
git clone https://github.com/microsoft/WSL2-Linux-Kernel --depth 1
cd WSL2-Linux-Kernel/tools/perf
make -j8
sudo cp perf /usr/local/bin

fay59

Here's a list of mildly interesting things about the C language that I learned mostly by consuming Clang's ASTs. Although surprises are getting sparser, I might continue to update this document over time.

There are many more mildly interesting features of C++, but the language is literally known for being weird, whereas C is usually considered smaller and simpler, so this is (almost) only about C.

1. Combined type and variable/field declaration, inside a struct scope [https://godbolt.org/g/Rh94Go]

struct foo {
   struct bar {
 int x;

onildoaguiar

About

Delete local branches that do not exist remotely.

$ git fetch --all --prune; git branch --verbose | grep ": gone]" | awk '{ print $1 }' | xargs --no-tags 1 git branch --delete --force

rgreenjr

-- show running queries (pre 9.2)
SELECT procpid, age(clock_timestamp(), query_start), usename, current_query 
FROM pg_stat_activity 
WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%' 
ORDER BY query_start desc;

-- show running queries (9.2)
SELECT pid, age(clock_timestamp(), query_start), usename, query 
FROM pg_stat_activity 
WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%' 

jboner

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