mahrens (Matthew Ahrens)
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User Since
Jul 24 2014, 3:11 AM (182 w, 8 h)

Recent Activity

Dec 5 2017

mahrens added a comment to D11124: WIP: ZSTD in ZFS.

So you only have one new compression value in the BP? Have you looked at how this interacts with L2ARC when compressed ARC is disabled? See arc_cksum_is_equal(), I don't think this will work right, because you won't be able to reproduce the on-disk compressed data without knowing the compression level.

Dec 5 2017, 4:56 PM

Sep 20 2017

mahrens added a comment to D12396: Default ABD chunk size.

@seanc OpenZFS/illumos has been at 4K chunk size since ABD was introduced. I'm not aware of any discussion around changing that.

Sep 20 2017, 3:55 PM · ZFS

Sep 17 2017

mahrens added a comment to D12396: Default ABD chunk size.

FYI - we use 1K ABD chunks at Delphix (on illumos), and we've found that up to 40% of memory can end up being wasted because of memory fragmentation. At least on illumos, the 1K ABD kmem cache will use slab size 4K (one page), so there are 4 chunks per slab. After eviction, we may have many partially-full slabs, which wastes the free chunks. We are considering implementing a kmem_move callback which would allow the free chunks to be consolidated, reducing the potential for memory waste. But it isn't done yet.

Sep 17 2017, 2:58 AM · ZFS

Jul 19 2016

mahrens added a member for ZFS: mahrens.
Jul 19 2016, 8:24 PM
mahrens added inline comments to D6533: zfs: step #1 of bringing zpl to full obedience of vfs.
Jul 19 2016, 8:24 PM

Jun 13 2016

mahrens committed rS301876: Add myself (mahrens) to calendar.freebsd.
Add myself (mahrens) to calendar.freebsd
Jun 13 2016, 11:36 PM

Dec 23 2015

mahrens accepted D4691: zdb: report an error if initialisation fails.
Dec 23 2015, 12:02 AM
mahrens added a comment to D4691: zdb: report an error if initialisation fails.

looks good. Happy to have this upstream too.

Dec 23 2015, 12:02 AM

Nov 10 2015

mahrens added a comment to D3478: GCC Warning - unused-but-set-variable.

You can use the instructions here: https://github.com/openzfs/openzfs to submit a pull request and get regression tests. Then solicit code reviews to developer@lists.illumos.org.

Nov 10 2015, 4:24 PM

Nov 2 2015

mahrens added a comment to D4074: Make 'zfs release' accept a filesystem instead of only snapshots.

What is the use case for this? AFAIK it isn't possible to create all those holds with one zfs command (there's just "zfs holds -r <snapshot>" which creates a hold on one snapshot per filesystem.

Nov 2 2015, 10:48 PM

Oct 25 2015

mahrens accepted D3994: Extend 'zfs holds -r' to accept a dataset, instead of only a snapshot as input.
Oct 25 2015, 7:51 PM
mahrens added inline comments to D3994: Extend 'zfs holds -r' to accept a dataset, instead of only a snapshot as input.
Oct 25 2015, 4:58 AM

Oct 24 2015

mahrens added a comment to D3994: Extend 'zfs holds -r' to accept a dataset, instead of only a snapshot as input.

This is a good start, but you also need to update the manpage and help message (see get_usage()).

Oct 24 2015, 5:09 AM

Jun 20 2015

mahrens accepted D2865: zfs_mount(MS_REMOUNT): protect zfs_(un)register_callbacks calls.
Jun 20 2015, 3:30 PM

Jun 18 2015

mahrens accepted D2839: illums compat: use flsl/flsll for highbit/highbit64.

Looks fine to me. FWIW, illumos appears to have flsll() in userland but not kernel. It's implemented similarly to highbit().

Jun 18 2015, 7:53 PM

Jun 11 2015

mahrens accepted D2722: Fix some clang warnings..
Jun 11 2015, 3:03 PM

Jun 10 2015

mahrens added inline comments to D2722: Fix some clang warnings..
Jun 10 2015, 10:02 PM

Mar 15 2015

mahrens retitled D2068: add mahrens as committer from to add mahrens as committer.
Mar 15 2015, 1:44 AM

Aug 7 2014

mahrens accepted D472: Quisece one printf warnings.
Aug 7 2014, 10:16 PM
mahrens added a comment to D472: Quisece one printf warnings.

looks good to me.

Aug 7 2014, 10:15 PM

Jul 24 2014

mahrens updated subscribers of D472: Quisece one printf warnings.
Jul 24 2014, 3:15 AM