Pavel Labath taught me that clang-format sorts headers automatically
using llvm's rules, and it's better not to have spaces between
So in this diff I'm removing those spaces and formatting them as well.
I used `clang-format -i` to format these files.
- Add the logic that parses all cpu context switch traces and produces blocks of continuous executions, which will be later used to assign intel pt subtraces to threads and to identify gaps. This logic can also identify if the context switch trace is malformed.
- The continuous executions blocks are able to indicate when there were some contention issues when producing the context switch trace. See the inline comments for more information.
- Update the 'dump info' command to show information and stats related to the multicore decoding flow, including timing about context switch decoding.
- Add the logic to conver nanoseconds to TSCs.
- Fix a bug when returning the context switches. Now they data returned makes sense and even empty traces can be returned from lldb-server.
- Finish the necessary bits for loading and saving a multi-core trace bundle from disk.
- Change some size_t to uint64_t for compatibility with 32 bit systems.
Tested by saving a trace session of a program that sleeps 100 times, it was able to produce the following 'dump info' text:
```
(lldb) trace load /tmp/trace3/trace.json (lldb) thread trace dump info Trace technology: intel-pt
thread #1: tid = 4192415
Total number of instructions: 1
Memory usage:
Total approximate memory usage (excluding raw trace): 2.51 KiB
Average memory usage per instruction (excluding raw trace): 2573.00 bytes
Timing for this thread:
Timing for global tasks:
Context switch trace decoding: 0.00s
Events:
Number of instructions with events: 0
Number of individual events: 0
Multi-core decoding:
Total number of continuous executions found: 2499
Number of continuous executions for this thread: 102
Errors:
Number of TSC decoding errors: 0
```
Differential Revision: https://reviews.llvm.org/D126267
I'm adding two new classes that can be used to measure the duration of long
tasks as process and thread level, e.g. decoding, fetching data from
lldb-server, etc. In this first patch, I'm using it to measure the time it takes
to decode each thread, which is printed out with the `dump info` command. In a
later patch I'll start adding process-level tasks and I might move these
classes to the upper Trace level, instead of having them in the intel-pt
plugin. I might need to do that anyway in the future when we have to
measure HTR. For now, I want to keep the impact of this change minimal.
With it, I was able to generate the following info of a very big trace:
```
(lldb) thread trace dump info Trace technology: intel-pt
thread #1: tid = 616081
Total number of instructions: 9729366
Memory usage:
Raw trace size: 1024 KiB
Total approximate memory usage (excluding raw trace): 123517.34 KiB
Average memory usage per instruction (excluding raw trace): 13.00 bytes
Timing:
Decoding instructions: 1.62s
Errors:
Number of TSC decoding errors: 0
```
As seen above, it took 1.62 seconds to decode 9.7M instructions. This is great
news, as we don't need to do any optimization work in this area.
Differential Revision: https://reviews.llvm.org/D123357
Walter Erquinigo