Re: bad performance on touch/cp file on XFS system

[Dave Chinner <david@fromorbit.com>]

On Mon, Aug 25, 2014 at 04:47:39PM +0800, Zhang Qiang wrote:
> I have checked icount and ifree, but I found there are about 11.8 percent
> free, so the free inode should not be too few.
> 
> Here's the detail log, any new clue?
> 
> # mount /dev/sda4 /data1/
> # xfs_info /data1/
> meta-data=/dev/sda4              isize=256    agcount=4, agsize=142272384

4 AGs

> icount = 220619904
> ifree = 26202919

And 220 million inodes. There's your problem - that's an average
of 55 million inodes per AGI btree assuming you are using inode64.
If you are using inode32, then the inodes will be in 2 btrees, or
maybe even only one.

Anyway you look at it, searching btrees with tens of millions of
entries is going to consume a *lot* of CPU time. So, really, the
state your fs is in is probably unfixable without mkfs. And really,
that's probably pushing the boundaries of what xfsdump and
xfs-restore can support - it's going to take a long tiem to dump and
restore that data....

With that many inodes, I'd be considering moving to 32 or 64 AGs to
keep the btree size down to a more manageable size. The free inode
btree would also help, but, really, 220M inodes in a 2TB filesystem
is really pushing the boundaries of sanity.....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs