diff options
Diffstat (limited to 'microkernel')
4 files changed, 80 insertions, 53 deletions
diff --git a/microkernel/viengoos/projects.mdwn b/microkernel/viengoos/projects.mdwn index 27dcc3e2..971206bb 100644 --- a/microkernel/viengoos/projects.mdwn +++ b/microkernel/viengoos/projects.mdwn @@ -8,58 +8,10 @@ Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled [[GNU Free Documentation License|/fdl]]."]]"""]] -[[!tag open_issue_viengoos]] - Some projects: -# Minor - -## New hash function - -The current hash function in libhurd-ihash results in a lot of -collisions when the hash table is 80% full. To overcome this, we keep -hash tables at most 30% full. This represents a fair amount of -overhead. Find a better algorithm. There can either be one that is -appropriate in the general case or one that works well in a relevant, -specific case, e.g., viengoos/object.c uses a hash to find the object -corresponding to a frame, which is keyed on its physical address. - -# Major - -## Address Space Management - -In Viengoos, a process's address space is managed entirely in user -space by the process itself. This creates two interesting problems: -dealing with circular dependencies resulting from having to manage the -address space data structures and accessing and manipulating the -address space data structures. - -First, managing the address space requires resources, which in turn -may require address space (e.g., data structures require memory which -require address space, etc.). We currently break this circular -dependency by trying to keep enough resources in reserve that -allocating resources for managing the address space never requires -more resources than are minimally in the reserve. The reserve is -currently chosen in an ad-hoc fashion. It would be nice to determine -it more systematically. Moreover, it would be nice to reduce the -cases in which a reserve is required. This may be possible by -restructuring some of the code. - -Second, the address space data structures are protected using a single -lock. This not only means that only a single thread can be updating -the address space at a time, but that if a thread faults and the -address space is locked, then the process dead locks! It should be -possible to at least walk the address space using lock-free -techniques. This requires updating the address space construction -code such that all addresses remain valid during any given -manipulation. Second, to avoid the mentioned dead-lock problem, we -try to ensure that accessing the data structures will never result in -a fault. This means protecting the stack. An alternative approach is -to use undo buffers. - -# Thesis - -## Capability aware compiler - -Modify, e.g., gcc to understand capability semantics and teach gcc how -to optimize it, e.g., how to batch and combine calls. +[[!inline +pages="microkernel/viengoos/projects/* and !microkernel/viengoos/projects/*/*" +show=0 +feeds=no +actions=yes]] diff --git a/microkernel/viengoos/projects/address_space_management.mdwn b/microkernel/viengoos/projects/address_space_management.mdwn new file mode 100644 index 00000000..2d00e4f4 --- /dev/null +++ b/microkernel/viengoos/projects/address_space_management.mdwn @@ -0,0 +1,40 @@ +[[!meta copyright="Copyright © 2008, 2009 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +[[!tag open_issue_viengoos]] + +In Viengoos, a process's address space is managed entirely in user +space by the process itself. This creates two interesting problems: +dealing with circular dependencies resulting from having to manage the +address space data structures and accessing and manipulating the +address space data structures. + +First, managing the address space requires resources, which in turn +may require address space (e.g., data structures require memory which +require address space, etc.). We currently break this circular +dependency by trying to keep enough resources in reserve that +allocating resources for managing the address space never requires +more resources than are minimally in the reserve. The reserve is +currently chosen in an ad-hoc fashion. It would be nice to determine +it more systematically. Moreover, it would be nice to reduce the +cases in which a reserve is required. This may be possible by +restructuring some of the code. + +Second, the address space data structures are protected using a single +lock. This not only means that only a single thread can be updating +the address space at a time, but that if a thread faults and the +address space is locked, then the process dead locks! It should be +possible to at least walk the address space using lock-free +techniques. This requires updating the address space construction +code such that all addresses remain valid during any given +manipulation. Second, to avoid the mentioned dead-lock problem, we +try to ensure that accessing the data structures will never result in +a fault. This means protecting the stack. An alternative approach is +to use undo buffers. diff --git a/microkernel/viengoos/projects/capability-aware_compiler.mdwn b/microkernel/viengoos/projects/capability-aware_compiler.mdwn new file mode 100644 index 00000000..b4e465d9 --- /dev/null +++ b/microkernel/viengoos/projects/capability-aware_compiler.mdwn @@ -0,0 +1,16 @@ +[[!meta copyright="Copyright © 2008, 2009 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled +[[GNU Free Documentation License|/fdl]]."]]"""]] + +[[!tag open_issue_viengoos]] + +Modify, e.g., gcc to understand capability semantics and teach gcc how +to optimize it, e.g., how to batch and combine calls. + +This project is deemed suitable for a thesis. diff --git a/microkernel/viengoos/projects/new_hash_function.mdwn b/microkernel/viengoos/projects/new_hash_function.mdwn new file mode 100644 index 00000000..1747511d --- /dev/null +++ b/microkernel/viengoos/projects/new_hash_function.mdwn @@ -0,0 +1,19 @@ +[[!meta copyright="Copyright © 2008, 2009 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +[[!tag open_issue_viengoos]] + +The current hash function in libhurd-ihash results in a lot of +collisions when the hash table is 80% full. To overcome this, we keep +hash tables at most 30% full. This represents a fair amount of +overhead. Find a better algorithm. There can either be one that is +appropriate in the general case or one that works well in a relevant, +specific case, e.g., viengoos/object.c uses a hash to find the object +corresponding to a frame, which is keyed on its physical address. |