lkml.org 
[lkml]   [2017]   [Sep]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: XFS mounted with 'discard' option - deleting fio test files slow
On Fri, Sep 08, 2017 at 09:34:02AM +1000, Dave Chinner wrote:
> 4k random write with direct IO. 5GB file. Probably got a million 4k
> extents in it. Which means XFS has sent a million tiny 4k discards
> to the device. Run 'xfs_bmap -vvp fio_test_file.*' to confirm.
>
> Don't use "-o discard" if you care about performance.

And your device sucks :)

Some numbers here:

https://events.linuxfoundation.org/sites/events/files/slides/discard_0.pdf

Discard will cause extra work, and for worst case sceanarios lots of
it. But some device handle that extra load very well.

\
 
 \ /
  Last update: 2017-09-08 09:17    [W:0.054 / U:0.896 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site