Paweł Dziepak's blog

New scheduler merged

Blog post by Paweł Dziepak on Tue, 2014-02-18 03:47
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As you undoubtedly know, my scheduler branch has been merged a month ago. Also, some important changes has been made since, including bug fixes and performance improvements. It is now time to sum up what already has been done, and show some long promised benchmark results. There are still some issues that need to be addressed, but I do not think that any of them is a major one.

Haiku meets 9th processor

Blog post by Paweł Dziepak on Fri, 2013-12-20 20:59
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It's been quite a long time since my last report so I think it is a good time to describe what I have been doing in the last two months. The main scheduler logic has been completed and now I am concentrating mainly on bug fixes, adjusting tunables and some minor improvements. I also removed gSchedulerLock, a spinlock I mentioned in my last post, and replaced it with more fine grained locking. An new interfaces for cpufreq and cpuidle modules has been created together with a cpufreq module for Intel Sandy Bridge or newer cores and cpuidle module for all processors that support C-states and invariant TSC. Furthermore, IRQs (including MSI) can be now directed to an arbitrary logical processor. Implementation of inter-processor interrupts has been improved so that it avoids acquiring any lock if it is not necessary and supports multicast interrupts. And, last but not least, 8 processor limit has been removed.

Scheduler work progress

Blog post by Paweł Dziepak on Mon, 2013-10-21 16:14
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Thanks to generosity of Haiku supporters, I will be able to continue my work on scheduler in November. It's high time I wrote a report about what has already been done. As it was mentioned before my work can be tracked in the scheduler branch in my repository. Commit descriptions and some comments in the scheduler code contain more detailed motivation behind some of the decisions I had to make. In this post, though, I will concentrate how my work looked so far and what I plan to do next.

Enhancing the scheduler

Blog post by Paweł Dziepak on Sat, 2013-09-07 20:17
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Soon I am going to work as a full-time Haiku developer on enhancing the scheduler. The goal is to improve performance of the whole system and finally deal with some long standing problems. To achieve this CPU affinity will be introduced what would make cache utilization better and I will implement scheduler strategies based on dynamic priorities what, hopefully, would once and for all deal with priority inversion. In addition to that, I want to make scheduler more power-aware. Haiku currently lacks low-level support for some of the more advanced power related features of CPUs but having scheduler ready for would save us from redesigning it later. Also, there are still ways to conserve energy without using the most recent technologies.

ASLR and DEP implemented

Blog post by Paweł Dziepak on Wed, 2013-04-17 22:37

Starting with hrev45522 address space layout randomization (ASLR) and data execution prevention (DEP) are available in Haiku. These two features, which have actually become a standard in any modern OS, make it much harder to exploit any vulnerability that may be present in an application running on Haiku thus generally improve system security.

NFSv4 client finally merged

Blog post by Paweł Dziepak on Fri, 2013-03-15 17:09

Earlier this week NFSv4 client I have been working on during the last year Google Summer of Code has been merged into the main Haiku repository and is now available in nightly images. The client supports all caching mechanisms available in the version 4 of NFS what means that it can get the most out of network connection and the server. Unfortunately due to limitations of the NFS protocol itself extended attributes are not supported yet.

NFSv4 client: final report

Blog post by Paweł Dziepak on Sun, 2012-08-26 18:46
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Since three quarter term I've added NFS-level support for named attributes what means that virtually all important NFS version 4 feature are now implemented, as I described them in my blog posts during the coding period. What still needs to be done is to improve support of Haiku's extended attributes and a lot of bugfixing. There is also a room for performance improvement and several possibilities to organize code in a better way.

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