Re: VFAT truncate performance

[OGAWA Hirofumi]

Mattias Rönnblom <hofors@xxxxxxxxxxxxxx> writes:

> extending files by ftruncate(2) runs very slow on VFAT file
> systems. On my USB harddisk w/ VFAT, it takes 14 seconds to extend an
> empty file to 1 GB. On a memory stick, it takes well over 4 minutes.
>
> My question is: is this problem on the conceptual level (ie there is
> no way of extending files on FAT that doesn't involve many disk
> operations) or is the current Linux fs driver suboptimal in this
> respect?

Unfortunately FAT doesn't support sparse file, so ftruncate(2) which
extend size needs to fill all clusters with zero, and write data.

This is limitation of FAT filesystem.
-- 
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/