Re: very slow file deletion on an SSD

joe.landman
2012-05-27T00:10:53Z

Ok. Will do in a few hours

Sent from my iPad

On May 26, 2012, at 8:07 PM, Dave Chinner <david@fromorbit.com> 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)?
>
> if not, can you use perf top to get an ida of the CPU usage profile
> duing the rm by doing:
>
> # perf record rm -f *
> .....
>
> and capturing the profile via:
>
> # perf report > profile.txt
>
> And attaching te profile.txt file so we can see where all the CPU
> time is being spent? You can find perf in your kernel source tree
> under the tools subdir....
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@fromorbit.com