Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Wed, 2015-06-10 at 15:06 -0700, Ming Lin wrote:
> On Wed, Jun 10, 2015 at 2:46 PM, Mike Snitzer <snitzer at redhat.com> wrote:
> > On Wed, Jun 10 2015 at 5:20pm -0400,
> > Ming Lin <mlin at kernel.org> wrote:
> >
> >> On Mon, Jun 8, 2015 at 11:09 PM, Ming Lin <mlin at kernel.org> wrote:
> >> > On Thu, 2015-06-04 at 17:06 -0400, Mike Snitzer wrote:
> >> >> We need to test on large HW raid setups like a Netapp filer (or even
> >> >> local SAS drives connected via some SAS controller). Like a 8+2 drive
> >> >> RAID6 or 8+1 RAID5 setup. Testing with MD raid on JBOD setups with 8
> >> >> devices is also useful. It is larger RAID setups that will be more
> >> >> sensitive to IO sizes being properly aligned on RAID stripe and/or chunk
> >> >> size boundaries.
> >> >
> >> > Here are tests results of xfs/ext4/btrfs read/write on HW RAID6/MD RAID6/DM stripe target.
> >> > Each case run 0.5 hour, so it took 36 hours to finish all the tests on 4.1-rc4 and 4.1-rc4-patched kernels.
> >> >
> >> > No performance regressions were introduced.
> >> >
> >> > Test server: Dell R730xd(2 sockets/48 logical cpus/264G memory)
> >> > HW RAID6/MD RAID6/DM stripe target were configured with 10 HDDs, each 280G
> >> > Stripe size 64k and 128k were tested.
> >> >
> >> > devs="/dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg /dev/sdh /dev/sdi /dev/sdj /dev/sdk"
> >> > spare_devs="/dev/sdl /dev/sdm"
> >> > stripe_size=64 (or 128)
> >> >
> >> > MD RAID6 was created by:
> >> > mdadm --create --verbose /dev/md0 --level=6 --raid-devices=10 $devs --spare-devices=2 $spare_devs -c $stripe_size
> >> >
> >> > DM stripe target was created by:
> >> > pvcreate $devs
> >> > vgcreate striped_vol_group $devs
> >> > lvcreate -i10 -I${stripe_size} -L2T -nstriped_logical_volume striped_vol_group
> >
> > DM had a regression relative to merge_bvec that wasn't fixed until
> > recently (it wasn't in 4.1-rc4), see commit 1c220c69ce0 ("dm: fix
> > casting bug in dm_merge_bvec()"). It was introduced in 4.1.
> >
> > So your 4.1-rc4 DM stripe testing may have effectively been with
> > merge_bvec disabled.
>
> I'l rebase it to latest Linus tree and re-run DM stripe testing.
Here is the results for 4.1-rc7. Also looks good.
5. DM: stripe size 64k
4.1-rc7 4.1-rc7-patched
------- ---------------
(MB/s) (MB/s)
xfs read: 784.0 783.5 -0.06%
xfs write: 751.8 768.8 +2.26%
ext4 read: 837.0 832.3 -0.56%
ext4 write: 806.8 814.3 +0.92%
btrfs read: 787.5 786.1 -0.17%
btrfs write: 722.8 718.7 -0.56%
6. DM: stripe size 128k
4.1-rc7 4.1-rc7-patched
------- ---------------
(MB/s) (MB/s)
xfs read: 1045.5 1068.8 +2.22%
xfs write: 1058.9 1052.7 -0.58%
ext4 read: 1001.8 1020.7 +1.88%
ext4 write: 1049.9 1053.7 +0.36%
btrfs read: 1082.8 1084.8 +0.18%
btrfs write: 948.15 948.74 +0.06%