On Wed, Apr 01, 2015 at 03:01:07PM -0400, Jeff Mahoney wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 4/1/15 2:44 PM, Brian Foster wrote: > > On Mon, Mar 30, 2015 at 03:11:06PM -0400, Jeff Mahoney wrote: > >> This tests tests four conditions where discard can potentially > >> not discard unused extents completely. > >> > >> We test, with -o discard and with fstrim, scenarios of removing > >> many relatively small files and removing several large files. > >> > >> The important part of the two scenarios is that the large files > >> must be large enough to span a blockgroup alone. It's possible > >> for an entire block group to be emptied and dropped without an > >> opportunity to discard individual extents as would happen with > >> smaller files. > >> > >> The test confirms the discards have occured by using a sparse > >> file mounted via loopback to punch holes and then check how many > >> blocks are still allocated within the file. > >> > >> Signed-off-by: Jeff Mahoney <je...@suse.com> --- > > > > The code looks mostly Ok to me, a few notes below. Those aside, > > this is a longish test. It takes me about 8 minutes to run on my > > typical low end vm. > > My test hardware is a 16 core / 16 GB RAM machine using a commodity > SSD. It ran pretty quickly.
Yup, I have a test VM like that, too. However, like many other people, I also have small VMs that share single spindles with other test VMs, so we need to cater for them, too. > >> + if [ "$FSTYP" = "btrfs" ]; then > >> + _run_btrfs_util_prog filesystem sync $tmpdir > >> + fi > >> + sync > >> + sync > > > > Any reason for the double syncs? > > Superstition? IIRC, at one point in what is probably the ancient past, > btrfs needed two syncs to be safe. I kept running into false failures > without both a sync and the btrfs filesystem sync, so I just hit the > "no really, just do it" button. Urk. If btrfs requires two sync passes to really sync data/metadata, then that's a bug that needs to be fixed. Let's not encode superstition or work around bugs that really should be fixed in the test code.... Cheers, Dave. -- Dave Chinner da...@fromorbit.com -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
