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content/blog/DebuggingAndPerformance.md

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+---
+title: "Debugging and Performance"
+date: 2019-06-15T10:59:30-04:00
+draft: false 
+---
+
+I've come to like the GNU Debugger (GDB) and the `perf` tool recently. This post will be a short summary of the various interesting commands you can use.
+
+## GNU Debugger
+
+To attach gbd to an existing process do the following
+
+```bash
+gdb -p pid_of_process
+```
+
+Otherwise you can start a new application
+
+```bash
+gdb name_of_executable
+```
+
+Once it loads it will bring you into it's own `REPL` environment. Usually once this comes up I find it useful to add breakpoints to the program. You can either do it by function name or by line number.
+
+```bash
+(gdb) break FunctionName
+```
+
+```bash
+(gdb) break code.cpp:81
+```
+
+If you just started a new application you can begin running the program with whatever arguments you wish
+
+```bash
+(gdb) run -arg1 -arg2
+```
+
+If you have attached to a process then you can continue its execution.
+
+```bash
+(gdb) continue
+```
+
+### Breakpoints
+
+If you have set a breakpoint, it will stop the processes' execution when it lands on the breakpoint. From here, we can take a look at what's on the stack, print variables, and do whatever other debugging we wish.
+
+**Print variables on stack:**
+
+```bash
+(gdb) info locals
+```
+
+**Print a specific variable:**
+
+```bash
+(gdb) print variable_name
+```
+
+**Show backtrace:**
+
+```bash
+(gdb) bt
+```
+
+**Continue on with program execution:**
+
+```bash
+(gdb) continue
+```
+
+## Perf
+
+I haven't played with `perf` as much but one thing I found that was cool was the `perf top` command. This command gives you samples of which function calls keeps the program the most busy.
+
+To attach to a process and show samples:
+
+```bash
+perf top -p pid -K
+```
+
+
+
+
+