Re: cp: performance improvement with small files

[Phillip Susi]

Hauke Laging wrote:
> Hello,
>
> I just read an interesting hint in the German shell Usenet group 
> (<address@hidden>). As I could not find anything about 
> that point in your mailing list archive I would like to mention it here.
>
> The author claims that he achieved a huge performance increase (more than 
> factor 10) when copying a big amount of small files (1-10 KiB) by sorting 
> by inode numbers first. This probably reduces the disk access time which 
> becomes the dominating factor for small files.

It depends on what filesystem you are using.  In ext3 this would help, 
but not on reiserfs, where there is no relationship between inode number 
and disk position.

In any case, this would significantly increase the complexity of cp for 
at best, dubious gains, so it isn't likely to happen.  Rather than sort 
by inode, it would be better if filesystems that would benefit from that 
would keep the directory list sorted that way so that the list would 
already be sorted when passed to cp.  IIRC, the defrag package sorts 
directories this way on ext2/3.