hi,
this is regarding the swap filesystem. soory i didn't have a copy
of the previous thread. The question is what file system the swap uses ?
Swap in fact doesn't have any filesystem as such.
The first 4kb (4096 bytes) of the swap space is used to maintain
information about the swap.Of this the last 10 bytes have the
signature "SWAP-SPACE" . The remaining 4086 bytes is used as a
bitmap.The swap blocks are considered as 4k blocks.So if there
is a 32 mb swap, the bits in the bitmap indicate where the
corresponding blocks are there.This bitmap information is read
from disk only once, when the system call swapon is called by the
init process and the kernel set up corrresponding data structures
which are used till the swap is removed by calling the system
call 'swapoff'.
The main parameters that are mainitained in the kernel data
structure are a bitmap and an char array.Bits are set in the
bitmap to indicate a read or write is taking place to a swap
block corresponding to the bit set. The char array corresponding
a swap block contains the count of many process have their pages
swapped out to this block. When the count is zero, the
correspodning swap block is free.
- sharma
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