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Bootloader: Add cache to ext2 inode data block indices 

This reduces the number of read calls with current kernel size from
~1700 to ~700 (60% performance boots). Loading the kernel is now alot
faster.
This commit is contained in:
Bananymous 2023-11-21 19:12:35 +02:00
parent f80bd040c8
commit 25485069e6
1 changed files with 43 additions and 1 deletions
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44
bootloader/bios/ext2.S
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@ -236,6 +236,10 @@ ext2_read_inode:
movl (ext2_inode_size), %ecx
rep movsb
# reset indirect cache to zero
movl $0, (ext2_inode_indirect_number)
.ext2_read_inode_done:
popal
ret
@ -249,6 +253,7 @@ ext2_data_block_index:
pushl %ecx
pushl %edx
pushl %esi
pushl %edi
# calculate max data blocks
movl (ext2_inode_buffer + i_size), %ecx
@ -309,6 +314,25 @@ ext2_data_block_index:
# ebx := index
# cx := depth
.ext2_data_block_index_indirect:
# calculate cache index ((index & 0xFF) | depth)
movl %ebx, %edx
andl $(~(EXT2_BLOCK_SIZE / 4 - 1)), %edx
orw %cx, %dx
# check whether this block is already cached
cmpl $0, (ext2_inode_indirect_number)
je .ext2_data_block_index_indirect_no_cache
cmpl %edx, (ext2_inode_indirect_number)
je .ext2_data_block_index_indirect_cached
.ext2_data_block_index_indirect_no_cache:
# update cache block number, will be cached when found
movl %edx, (ext2_inode_indirect_number)
# eax := current block
# ebx := index
# cx := depth
.ext2_data_block_index_indirect_loop:
call ext2_read_block
# store depth and index
@ -342,7 +366,13 @@ ext2_data_block_index:
popl %ebx
popw %cx
loop .ext2_data_block_index_indirect
loop .ext2_data_block_index_indirect_loop
# cache last read block
movw $ext2_block_buffer, %si
movw $ext2_inode_indirect_buffer, %di
movw $EXT2_BLOCK_SIZE, %cx
rep movsb
jmp .ext2_data_block_index_done
@ -358,7 +388,13 @@ ext2_data_block_index:
movl $0, %eax
jmp .ext2_data_block_index_done
.ext2_data_block_index_indirect_cached:
movl $ext2_inode_indirect_buffer, %esi
andl $(EXT2_BLOCK_SIZE / 4 - 1), %ebx
movl (%esi, %ebx, 4), %eax
.ext2_data_block_index_done:
popl %edi
popl %esi
popl %edx
popl %ecx
@ -681,9 +717,15 @@ ext2_looking_for_msg:
.section .bss
.align EXT2_BLOCK_SIZE
ext2_block_buffer:
.skip EXT2_BLOCK_SIZE
ext2_inode_indirect_buffer:
.skip EXT2_BLOCK_SIZE
ext2_inode_indirect_number:
.skip 4
ext2_partition_first_sector:
.skip 8