very slow file deletion on an SSD

[Joe Landman]

On 05/27/2012 12:07 PM, Eric Sandeen wrote:
> On 5/27/12 9:59 AM, joe.landman at gmail.com wrote:
>> This is going to be a very fragmented file.  I am guessing that this
>> is the reason for the long duration delete.   I'll do some more
>> measurements before going to 3.4.x as per Eric's note.
>
> filefrag -v should also tell you how many fragments, and because it
> uses fiemap it probably won't run into the same problems.
>
> But it sounds like we can just assume very high fragmentation.
>
> It's not addressing the exact issue, but why are the files so fragmented?
> Are they very hole-y or is it just an issue with how they are written?
> Perhaps preallocation would help you here?

... and one pass with xfs_fsr seems to have "fixed" the problem

[root at siFlash test]# xfs_fsr
xfs_fsr -m /proc/mounts -t 7200 -f /var/tmp/.fsrlast_xfs ...
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
/data/1 start inode=0
/data/2 start inode=0
/data/3 start inode=0
Completed all 10 passes
[root at siFlash test]# filefrag  1.r.48.0
1.r.48.0: 1 extent found

[root at siFlash test]# rm -f 1.r.48.0

(very fast)

-- 
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics Inc.
email: landman at scalableinformatics.com
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