OGAWA Hirofumi <[EMAIL PROTECTED]> wrote: > DervishD <[EMAIL PROTECTED]> writes:
>> Probably it's stupid to update the free clusters count at mount time >> (sorry if so...) but it looks like a good idea to me. And of course, I >> don't mean to update the value _on disk_, but the kernel's idea of free >> clusters (so even FAT filesystems mounted R/O will report correct >> values). > > It would add the limitation to following simple usage, > > # mount -t vfat /dev/sda1 /mnt > # cp -a * /mnt > # umount > > if /dev/sda1 was the large and slow device, "mount" will need several > minutes to counts free clusters. I think the user will be hard to > accept the several minutes at "mount". I simulated recalculating the FAT using a suboptimal perl script on my 32 GB FAT32 partition on a 40 GB drive. The results should show the worst case for my system. The results were below 2 seconds (optimized perl at 0.5 s) on my AMD Athlon XP 2400+. (BTW: I don't think the device speed itself will be relevant in many cases even if you'd asume a slow link, since you'll need to read the FAT anyway.) I think this is acceptable, and on this system, I'd like to enable recalculating by default. On slower systems, you'll need to chose another default. I think you'll want that option as a module parameter to make all users happy. And while you're at it, fmask and dmask are good candidates for module parameters, too.-) # echo 3 > /proc/sys/vm/drop_caches # /usr/bin/time sh -c "dd if=/dev/hda2 bs=$((77834925/64)) count=4 | perl -e '"'use POSIX;while (sysread STDIN,$x,4) {$n++ if $x eq "\0\0\0\0"} print $n*32,"\n"'\' 4+0 records in 4+0 records out 13954720 0.76user 0.60system 0:01.95elapsed 69%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (8major+1583minor)pagefaults 0swaps # /usr/bin/time sh -c "dd if=/dev/hda2 bs=$((77834925/64)) count=4 | perl -e '"'use POSIX;while (sysread STDIN,$x,4) {$n++ if $x eq "\0\0\0\0"} print $n*32,"\n"'\' 4+0 records in 4+0 records out 13955392 0.74user 0.69system 0:01.50elapsed 95%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+1591minor)pagefaults 0swaps # /usr/bin/time sh -c "dd if=/dev/hda2 bs=$((77834925/64)) count=4 | perl -e '"'use POSIX;while (sysread STDIN,$x,4096) {for (unpack "L*",$x){$n++ if !$_}} print $n*32,"\n"'\' 4+0 records in 4+0 records out 13955392 0.43user 0.06system 0:00.50elapsed 97%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+1599minor)pagefaults 0swaps -- The worse the weather, the more you are required to be out in it. Friß, Spammer: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/