Re: very slow file deletion on an SSD

Eric Sandeen
2012-05-27T02:40:10Z

On 5/26/12 8:49 PM, Joe Landman wrote:
> On 05/26/2012 08:07 PM, Dave Chinner wrote:
>> On Sat, May 26, 2012 at 07:25:55PM -0400, Joe Landman wrote:
>>> [root@siFlash test]# ls -alF | wc -l
>>> 59
>>> [root@siFlash test]# /usr/bin/time rm -f *
>>> ^C0.00user 8.46system 0:09.55elapsed 88%CPU (0avgtext+0avgdata
>>> 2384maxresident)k
>>> 25352inputs+0outputs (0major+179minor)pagefaults 0swaps
>>
>> It's burning an awful lot of CPU time during this remove.
>>
>>> [root@siFlash test]# ls -alF | wc -l
>>> 48
>>
>> So, 48 files were removed, it was basically CPU bound and one took
>> 2.6 seconds.
>>
>> So, how big are the files, and does the one that took 2.6s have tens
>> of thousands of extents ('xfs_bmap -vp *' will dump the extent maps
>> for all the files)?
>
> Getting some sort of out of memory error with bmap
>
> [root@siFlash test]# ls -alF
> total 50466476
> drwxr-xr-x 2 root root 4096 May 26 21:40 ./
> drwxr-xr-x 3 root root 17 May 26 19:32 ../
> -rw------- 1 root root 1073741824 May 26 19:36 2.r.49.0
...

<snip>

> [root@siFlash test]# ls -alF > x
>
> [root@siFlash test]# xfs_bmap -vp x
> x:
> EXT: FILE-OFFSET BLOCK-RANGE AG AG-OFFSET TOTAL FLAGS
> 0: [0..7]: 212681896..212681903 2 (7555752..7555759) 8 01111
>
> [root@siFlash test]# xfs_bmap -vp 2.r.96.0
> xfs_bmap: xfsctl(XFS_IOC_GETBMAPX) iflags=0x4 ["2.r.96.0"]: Cannot allocate memory

Try filefrag -v maybe, if your e2fsprogs is new enough.

Trying to remember, ENOMEM in bmap rings a bell... but this is possibly indicative of an extremely fragmented file.

-Eric