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[[!meta title="Google Summer of Code 2010"]]

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DragonFly BSD is participating in the Google Summer of Code program for 2010.

The [[GSoC Projects Page|/docs/developer/GSoCProjectsPage/]] [Projects Page](/docs/developer/ProjectsPage/) are potential sources of ideas.

Have a look at our SoC pages from [[2008|docs/developer/GoogleSoC2008/]], [[2009|docs/developer/gsoc2009]] and [[2010|docs/developer/gsoc2010]] to get an overview about prior year's projects.

For more details on Google's Summer of Code: [Google's SoC page](http://socghop.appspot.com/)

Note to prospective students: These project proposals are meant to be a first approximation; we're looking forward to your own suggestions (even for completely new directions) and will try to integrate your ideas to make the GSoC project more interesting to all parties. Even when a proposal is very specific about the goals that must be achieved and the path that should be taken, these are always negotiable. Keep in mind that we have tried to limit our proposals to those that (based on our past experience) are appropriate for the GSoC program.

Legend:

* Prerequisites: knowledge that the student should have before starting the project. It may be possible to acquire the knowledge in the course of the project, but the estimated difficulty would increase substantially. On the bright side, you can expect to have a much deeper understanding of these fields (and gain some real-world experience) after you successfully complete the respective project.
* Difficulty: Estimated difficulty of the project, taking into account the complexity of the task and the time constraints of the GSoC program.
* Contact point: The person you should contact for any further information or clarifications.

#### Project ideas

##### VFS Quota System
* Create a new kernel subsystem to manage quota's in a filesystem agnostic manner by interfacing with the kernel VFS layer.
* Create filesystem-agnostic quota support tools for userland that obtain information in the same manner as eg: du(1) instead of parsing the filesystem internals directly as the existing quota tools do (see quotacheck(8), repquota(8), edquota(8), ...).
* The quota file storage can be modeled after the existing UFS code that does the same, but should use the more general bytes, files and/or directories metrics instead of the somewhat UFS-specific blocks and inodes.

Meta information:

* Prerequisites: C, introductory filesystems internals
* Difficulty: Moderate
* Contact point: Samuel J. Greear <sjg@thesjg.com>

---

##### HAMMER Data dedup

The HAMMER filesystem is very efficient in sharing data between its fine-grained
snapshots, but when you copy (or otherwise duplicate) a file or directory tree, the data
is no longer shared. This is suboptimal because then we make poor use of disk space
and the same data gets cached multiple times wasting precious RAM space.

The goal of this project is to add a data de-duplication mechanism to the HAMMER
filesystem. A reasonable approach would be to detect potential data matches using
CRCs during pruning runs. Then you could verify there is actual duplication of data
(i.e. the match is not a false positive), collapse the B-Tree data reference and account for the additional reference in the allocation blockmap.

BSD kernels cache data on a per-vnode basis, possibly investigate methods by which de-duplication could be extended into the vnode layer.

Meta information:

* Prerequisites: C, modern filesystem internals
* Difficulty: Moderate
* Contact point: dillon

---

##### Implement i386 32-bit ABI for x86_64 64-bit kernel
* Add a 32-bit syscall table which translates 32-bit
  system calls to 64-bit.
* Add support for 32 bit compatibility mode operation
  and ELF binary detection.

The idea here is to support the execution of 32 bit DragonFly binaries in 64 bit DragonFly environments, something numerous other operating systems have done.  Several things must be done to support this.  First, the appropriate control bits must be set to execute in 32-bit compatibility mode while in usermode instead of 64-bit mode.  Second, when a system call is made from 32-bit mode a translation layer is needed to translate the system call into the 64-bit requivalent within the kernel.  Third, the signal handler and trampoline code needs to operate on the 32-bit signal frame.  Fourth, the 32 and 64 bit ELF loaders both have to be in the kernel at the same time, which may require some messing around with procedure names and include files since originally the source was designed to be one or the other.

There are several hundred system calls which translates to a great deal of 'grunt work' when it comes time to actually do all the translations.

Meta information:

* Prerequisites: C
* Difficulty: Difficult (lots of moving parts, particularly the trapframes)
* Contact point: dillon

---

##### Implement ARC algorithm extension for the vnode free list
* Vnode recycling is LRU and can't efficiently handle data sets which
  exceed the maxvnode limit.  When the maxvnode limit is reached the kernel
  starts throwing away cached vnodes along with their VM objects (and thus
  all related cached file data).

* What we would like to do is implement an ARC algorithm for the free
  vnodes to determine which ones to throw away and potentially combine
  this with further caching of the related VM object even after the vnode
  is thrown away by associating it with a mount point and inode number,
  until memory pressure forces all of its pages out.

* For this project the student can choose to just implement the VM object
  retention portion and not try to implement an ARC algorithm (which can
  be considerably more complex).

Meta information:

* Prerequisites: C, OS internals
* Difficulty: Modest without ARC (Very difficult with ARC)
* Contact point: dillon

---

##### Implement swapoff
* We have swapon to add swap space, we need a swapoff to
  remove it.

Meta information:

* Prerequisites: C, elementary OS memory management
* Difficulty: Modest
* Contact point: dillon

Status:

* In-progress

---

##### Make DragonFly NUMA-aware 

* Parse related ACPI tables 
* NUMA-aware memory allocation
* References:
[ACPI SLIT parser](http://mail-index.netbsd.org/tech-kern/2009/11/23/msg006518.html)
[ACPI SRAT parser](http://mail-index.netbsd.org/tech-kern/2009/11/23/msg006517.html)
[NetBSD NUMA diff](http://www.netbsd.org/~cegger/numa2.diff)
[NetBSD NUMA x86 diff](http://www.netbsd.org/~cegger/numa_x86.diff) (These patches now in NetBSD tree)

Meta information:

* Prerequisites: C, introductory computer architecture
* Difficulty: Easy
* Contact point: kernel@crater.dragonflybsd.org

---


##### Port valgrind to DragonFlyBSD

Valgrind is a very useful tool on a system like DragonFly that's under heavy development. Since valgrind is very target specific, a student doing the port will have to get acquainted with many low level details of the system libraries and the user<->kernel interface (system calls, signal delivery, threading...). This is a project that should appeal to aspiring systems programmers. Ideally, we would want the port to be usable with vkernel processes, thus enabling complex checking of the core kernel code.

The goal of this project is to port valgrind to the DragonFlyBSD platform so that at least the memcheck tool runs sufficiently well to be useful. This is in itself a challenging task. If time remains, the student should try to get at least a trivial valgrind tool to work on a vkernel process.

Meta information:

* Prerequisites: C, x86 assembly, low-level OS internals
* Difficulty: Hard
* Contact point: Aggelos Economopoulos <aoiko@cc.ece.ntua.gr>

---

##### Adapt pkgsrc to create a package system with dependency independence.
* Create a set of tools that modifies how the pkgsrc packages are installed, allowing for the ability to upgrade individual packages, without stopping applications that depend on said packages from working. One method of achieving this is detailed at http://www.dragonflybsd.org/goals/#packages but other methods may be possible. PC-BSD have written a tool called PBI Builder which modifies FreeBSD ports for their dependency independence PBI system, this could be used as a starting point for the DragonFly BSD tools.

Meta information:

* Prerequisites: C
* Difficulty: ?
* Contact point: kernel@crater.dragonflybsd.org

---

##### Implement virtio drivers on DragonFly to speed up DragonFly as a KVM guest

As virtualization is coming more and more and KVM will be a strong player in that field,
we want DragonFly to have top-notch support for this virtualization platform. For this
purpose, we'd like to have a virtio-based implementation of a paravirtualized disk and
network driver. [virtio](http://www.ibm.com/developerworks/linux/library/l-virtio/index.html)
is an abstraction to a ring buffer that is shared between the host and the guest. On top of this
abstraction, one can build a variety of paravirtualized devices, as specified in
[virtio-spec](http://ozlabs.org/~rusty/virtio-spec/virtio-spec-0.8.6.pdf).

The goal of this project is to create a virtio-ring implementation and then to implement drivers
for the network and block devices described in the specification linked to above. This is a great
project for a student who wants to get experience writing (real-world, high-performance) device
drivers without having to deal with the quirks of real hardware.

Meta information:

* Prerequisites: C, elementary OS internals
* Difficulty: Easy
* Contact point: Aggelos Economopoulos <aoiko@cc.ece.ntua.gr>, kernel@crater.dragonflybsd.org

---

##### Port PUFFS from FreeBSD/NetBSD

* http://www.netbsd.org/docs/puffs/
* This would make many userspace filesystems available to DragonFly, e.g. sshfs to mention only one.

Meta information:

* Prerequisites: C, elementary OS internals
* Difficulty: Medium
* Contact point: Michael Neumann <mneumann@ntecs.de>

---

##### Make vkernels checkpointable

* See checkpt(1).
* Implement save and restore of segment registers so that threaded applications may be checkpointed. The segment registers support TLS. There are potential security concerns here.
* Teach the checkpt system call how to checkpoint multiple vmspaces.
* Add code to the vkernel which gets triggered upon reception of a SIGCKPT signal to dump/load e.g. the current state of network drivers.
* This would allow us to save and restore or even migrate a complete DragonFly operating system running on the vkernel platform.
This could be especially handy on laptops (if we'd get X11 operating in vkernels).
* See also: http://www.dragonflybsd.org/docs/developer/CheckpointFeatures/

Meta information:

* Prerequisites: C, OS internals
* Difficulty: Medium
* Contact point: Michael Neumann <mneumann@ntecs.de>
* References: [1](http://leaf.dragonflybsd.org/mailarchive/kernel/2007-02/msg00073.html) [2](http://leaf.dragonflybsd.org/mailarchive/users/2007-02/msg00034.html)

---

##### HAMMER compression

* Compress blocks as they get written to disk.
* Only file data (rec_type == DATA) should be compressed, not meta-data.
* the CRC should be that of the uncompressed data.
* ideally you'd need to associate the uncompressed data with the buffer cache buffer somehow, so that decompression is only performed once.
* compression could be turned on a per-file or per-pfs basis.
* gzip compression would be just fine at first.

Doing compression would require flagging the data record as being compressed and also require double-buffering since
the buffer cache buffer associated with the uncompressed data might have holes in it and otherwise referenced by user
programs and cannot serve as a buffer for in-place compression or decompression.

The direct read / direct write mechanic would almost certainly have to be disabled for compressed buffers and the
small-data zone would probably have to be used (the large-data zone is designed only for use with 16K or 64K buffers).

Meta information:

* Prerequisites: C, filesystem internals
* Difficulty: Difficult
* Contact point: Michael Neumann <mneumann@ntecs.de>

---


##### Port usb4bsd
* Port the whole usb4bsd stuff to DragonFly, as our own usb stack is too outdated.

* The usb4bsd branch of hselasky (?) has several userland wrappers and quite good abstraction to simplify the porting.

Meta information:

* Prerequisites: C, OS internals
* Difficulty: Moderate
* Contact point: kernel@crater.dragonflybsd.org

---

##### Userland System V Shared Memory / Semaphore / Message Queue implementation
* Implement some or all of these subsystems in their entirety, or as completely as possible in userland using a daemon, mmap and the DragonFly umtx_sleep(2)/umtx_wakeup(2) or other userland facilities.
* Any security or other major hurdles to this approach that would likely have to be implemented in-kernel should be noted in the students application.
* Test and benchmark the new facilities with heavy SysV consumers such as PostgreSQL
* Identify performance tradeoffs made in the userland implementation versus the existing kernel implementation. If time permits identify and apply solutions to these tradeoffs so that the userland implementation performs on par with or better than the kernel implementation.

Meta information:

* Prerequisites: C, x86 assembly
* Difficulty: Moderate
* Contact point: Samuel J. Greear <sjg@thesjg.com>

---


##### Update our interrupt routing and PCI code
* Update our interrupt routing to ACPI interrupt routing instead of relying on the mptable exclusively
* Update the PCI code to take advantage of MSI (Message Signalled Interrupts)

Meta information:

* Prerequisites: C, OS internals 
* Difficulty: Hard
* Contact point: kernel@crater.dragonflybsd.org

---

##### Proportional RSS

The Resident Stack Size displayed by top keeps track of the number of resident pages in
a certain process's adress space. It is very useful to locate memory hogs, but doesn't take
into account page sharing. For example, if N processes map library L and L's resident pages
are 1G, this 1G is added to the RSS of all N processes. A more useful number would be the
Proportional (or Effective) RSS, for which we divide the number of mapped shared pages by
the number of processes sharing each page. So in the previous example we would add 1GB/N
to each process that has L mapped.

The goal of this project is to hack the kernel to allow for effective calculation of the
Proportional RSS and modify top to use it in addition to the RSS (i.e. it should display it by
default and be able to sort based on it).

Meta information:

* Prerequisites: C, Elementary OS internals
* Difficulty: Easy
* Contact point: Aggelos Economopoulos <aoiko@cc.ece.ntua.gr>

Status:

* Possibly in-progress

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 (please add)