memory managment in servers?

23 Nov 94 14:22:42 -0100

Hello all,

I'm the guy who is trying to port the Linux ext2 filesystem to VSTa
(currently 1.3.2).  Assuming i will not give it up (i only work on it
at home on my spare time) i have a question regarding memory managment
in VSTa?

0. How does the swapping actually work. I believe i begin to
understand the filesystem protocol designed for that (ie FS_ABSREAD
FS_ABSWRITE and FS_FID) but i don't know how it is used?

1. Who is deciding the swapping (ie paging) policy? In other words,
who decide of the paging strategy (FIFO, best fit, etc)? Is it the
kernel or a dedicated swap server? (I think that Andys recommended me
to not use it currently since there are some bugs in the swap code).

2. Assuming a filesystem server is booted (perhaps some day a foolish
guy would even install my ext2fs as a boot server ie in
/boot/boot.lst) i believe it can't swap, so it works (hence malloc) in
physical memory, not in virtual memory. Can somebody confirm or
explain if i'm wrong.

3. I wish and am prepared to have some kind of memory-low
message. Does such a beast exists? I mean that my ext2fs allocate
dynamically (block and inode) cache and free them on a age basis (ie
it free the oldest unused block and inode in server memory -not on
disk). So it is very easy to me to handle a PLEASE_GIVE_BACK(N Kbytes)
message asking to free at least N kilobytes - i could also handle a
simpler MEMORY_LOW message asking to free as much memory as i can.

4. What exactly are VSTa events and notifies? I guess they generalize
posix signals in a message like fashion but i don't grap an exact
picture of them (eg can they be blocked, delayed, are they reliable,
sendable by anyone).

Linuxing and VSTaling at home only.


Basile STARYNKEVITCH   ----  Commissariat a l Energie Atomique
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