Haiku gets tons of performance fixes, new FAT driver from FreeBSD, and a lot more

There’s a new Haiku activity report, and it’s a big one. A lot of bottlenecks and performance issues were addressed recently, and the list is too long and detailed for me to cover everything. Haiku developer Waddlesplash does a great job in this report detailing the various things he worked on to solve some of these bottlenecks and performance issues, and they cover everything from speeding up the readv and writev I/O calls, fixing an issue with the kernel’s device_manager lock, improving ELF symbol lookup by implementing the DT_GNU_HASH hash table, and much more.

As part of working on these performance issues, Waddlesplash also fixed up Haiku’s CPU time profiler.

Haiku has a built-in CPU time profiler (just called profile.) Unfortunately, it’s been rather broken for years, regularly outputting data that was either empty or just didn’t make any sense. In order to use it to try and track down some of the other bottlenecks, I spent a bunch of time fixing various bugs in it, as well as the debugger support code that it relies on to function, including to stack trace collection, buffer flushing, symbol lookup, scheduler callbacks, image load reporting, and more. I also implemented userspace-only profiling (ignoring kernel stack frames entirely), fixed some output buffer sizing issues, and fixed a race condition in thread resumption that also affected strace.

While it isn’t perfect, it’s much better than before, and can now be used to profile applications and the kernel to see where CPU time is being spent; and notably it now checks the thread’s CPU time counters to detect if it “missed” profiling ticks, and if so how many.
↫ Haiku’s website

Beyond these performance fixes, there’s a ton of other improvements and fixes, from better handling of HiDPI displays in HaikuDepot, improvements to CharacterMap, fixing subtitles in MediaPlayer, and tons more. Of course, there’s the bevy of driver fixes, including a major overhaul of the FAT driver, which was still largely based on old, original BeOS code because Be used the FAT driver as sample code. Haiku’s FAT driver is now based on FreeBSD’s FAT driver, which addressed a whole slew of issues.

This isn’t even all of it – there’s so much more in this month’s activity report, so definitely head on over and give it a read.