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-rw-r--r--user/Maksym_Planeta.mdwn41
1 files changed, 30 insertions, 11 deletions
diff --git a/user/Maksym_Planeta.mdwn b/user/Maksym_Planeta.mdwn
index 707507a7..6f9bf3ec 100644
--- a/user/Maksym_Planeta.mdwn
+++ b/user/Maksym_Planeta.mdwn
@@ -13,16 +13,6 @@ License|/fdl]]."]]"""]]
## 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.
-
[[defpager|http://www.bddebian.com:8888/~hurd-web/user/Maksym_Planeta/#defpager81111]]
## Steps
@@ -41,6 +31,21 @@ License|/fdl]]."]]"""]]
Symlinks behavior: [[links|http://www.bddebian.com:8888/~hurd-web/user/Maksym_Planeta/#links81111]]
+ 8.11.11 Symlinks work.
+
+4. Control of used space by tmpfs.
+
+ TODO: Make tmpfs use not more space than it was allowed.
+
+5. Thread safety.
+
+ TODO: During execution tmpfs hangs in random places. The most possible is variant is deadlocks,
+ because nothing was undertaken for thread safety.
+
+6. After sometime of inactivity tmpfs exits.
+
+ TODO: Find out why and correct this.
+
#Debugging
To debug tmpfs, using libraries from "$PWD"/lib and trace rpc:
@@ -49,6 +54,7 @@ To debug tmpfs, using libraries from "$PWD"/lib and trace rpc:
LD_LIBRARY_PATH="$PWD"/lib gdb tmpfs/tmpfs 698
For debugging ext2fs:
+
settrans --create --active ramdisk0 /hurd/storeio -T copy zero:32M && \
/sbin/mkfs.ext2 -F -b 4096 ramdisk0 && \
settrans --active --orphan ramdisk0 /usr/bin/env LD_LIBRARY_PATH="$PWD"/lib utils/rpctrace -I /usr/share/msgids/ \
@@ -76,6 +82,20 @@ For debugging ext2fs:
(10:32:35) braunr: baz -> bar
### defpager<a id="defpager81111"/>
+
+ earlier:
+ <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.
+
+ ...
+
(10:36:14) mcsim: who else uses defpager besides tmpfs and kernel?
(10:36:27) braunr: normally, nothing directly
(10:37:04) mcsim: than why tmpfs should use defpager?
@@ -89,7 +109,6 @@ For debugging ext2fs:
(10:41:27) braunr: anonymous memory uses swap space as its backing store too
(10:43:47) braunr: but be aware that this part of the vm system is known to have deficiencies
(10:44:14) braunr: which is why all mach based implementations have rewritten their default pager
- (10:44:41) youpi: ArneBab: the intro is already in in my qemu image
(10:45:11) mcsim: what kind of deficiencies?
(10:45:16) braunr: bugs
(10:45:39) braunr: and design issues, making anonymous memory fragmentation horrible