FAT-fs performance

From: jdrzik@egarden.cz
Date: Sat Jul 29 2000 - 11:25:55 EST


I have this problem with FAT filesystem, when I create iso file from FAT
filesystrm to FAT fs and this file is bigger then 100MB there is big
slowdown with 2.2.x kernels.

This command with default value of FAT_CACHE in
include/linux/msdos_fs.h:24: :#define FAT_CACHE 8 /* FAT cache size */

time mkisofs -J -a -o /mnt/fat/out.iso /mnt/fat

20.85user 2948.56system 55:20.51elapsed 89%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (154090major+1065minor)pagefaults 722swaps

and when I change this value to
#define FAT_CACHE 64 /* FAT cache size */

25.25user 227.55system 11:27.61elapsed 36%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (157629major+739minor)pagefaults 62swaps

Is there any reason for so low value of FAT_CACHE by default ?

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