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| -rw-r--r-- | user/Maksym_Planeta.mdwn | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/user/Maksym_Planeta.mdwn b/user/Maksym_Planeta.mdwn index 64dc6e19..477f11ed 100644 --- a/user/Maksym_Planeta.mdwn +++ b/user/Maksym_Planeta.mdwn @@ -9,11 +9,31 @@ is included in the section entitled [[GNU Free Documentation License|/fdl]]."]]"""]] [[!toc]] -Notes on tmpfs -============== +#Notes on tmpfs + +## mach-defpager + + <tschwinge>: 1. On every system there is a ``default pager'' (mach-defpager). That one is responsible + for all ``anonymous memory''. For example, when you do malloc(10 MiB), and then there is memory pressure, + this 10 MiB memory region is backed by the default pager, whose job then is it to provide the backing store for this. + <tschwinge>: This is what commonly would be known as a swap partition. + <tschwinge>: And this is also the way tmpfs works (as I understand it). + <tschwinge>: malloc(10 MiB) can also be mmap(MAP_ANONYMOUS, 10 MIB); that's the same, essentially. + <tschwinge>: Now, for ext2fs or any other disk-based file system, this is different: + <tschwinge>: The ext2fs translator implements its own backing store, namely it accesses the disk for storing + changed file content, or to read in data from disk if a new file is opened. + +## Steps + +1. Find out what causes crashes in tmpfs with defpager + +2. Write own pager + + 6.11.11 Reading/writing for files that fit in vm_page_size works #Debugging To debug tmpfs, using libraries from "$PWD"/lib and trace rpc: -settrans -ca foo /usr/bin/env LD_LIBRARY_PATH="$PWD"/lib utils/rpctrace -I /usr/share/msgids/ tmpfs/tmpfs 1M + settrans -ca foo /usr/bin/env LD_LIBRARY_PATH="$PWD"/lib utils/rpctrace -I /usr/share/msgids/ tmpfs/tmpfs 1M + LD_LIBRARY_PATH="$PWD"/lib gdb tmpfs/tmpfs 698 |