16.04 SSD Re: Upstart issues with Ubuntu 14.04.

Peter Petrakis peter.petrakis at gmail.com
Sat Sep 10 16:05:38 EDT 2016


On Sat, Sep 10, 2016 at 12:40 AM, Bill Ricker <bill.n1vux at gmail.com> wrote:

> On Sep 9, 2016 23:05, "Joshua Judson Rosen" <rozzin at hackerposse.com>
> wrote:
> >
> > On 09/09/2016 12:06 PM, Richard Kolb II wrote:
> > > Not exactly related, but I just switched from windows 7 on my primary
> > > machine to Ubuntu 16.x LTS. I found it horribly slow, which surprised
> > > me considering it's a faster machine, more ram, and an SSD, over my
> > > 14.x LTS machine.
> >
> > Does it perhaps have a worse graphics card--or perhaps even just
> > a _worse-supported_ graphics card? Bottlenecks can be
> > at the near end just as well as they can be at the far end....
>
> If you run "Additional Drivers", it will inform you if there is a nonlibre
> driver that might perform better.
>

+1.

When I used to do hardware enablement for Canonical, I was initially
dismayed
that we were going out of our way to integrate and qualify binary video
drivers.
Then I saw the difference it makes for discrete graphics controllers
(nvidia/ati),
especially on laptops. Having said that, I run all Intel with UMA graphics
and
can drive my 4K monitor with a 5 year old thinkpad.

Checkout the hardware cert db before your next buy.
http://www.ubuntu.com/certification/desktop/ .
If it's there, it'll just work. If the platform chips are the same, it'll
"probably" just work too.
There's a little lag for the binary video drivers making it into the repos
as getting pre-install image done has priority.

> xenial 16.04LTS with SSD, Intel graphics is amazing fast here.
> (Intel NUK6i7kyk and EVO950pro nvme m.2 SSD . mDP works fine, HDMI didn't
> do 4k for me. )
>
> Don't be fooled by SATA mode m.2 SSDs, they're better than rotary drives
> but they aren't the m.2 you are looking for!
>

You ought to be able to get close to 500MB/s sequential write performance
from a good SSD.

Here's a micron m500 that I beat on a lot.

Using this fio file as a starting point:
http://tfindelkind.com/2015/08/24/fio-flexible-io-tester-part8-interpret-and-understand-the-resultoutput/

I have a tweaked one somewhere, I just can't find it atm.

# sequential 4k write
# set readwrite=write
# DESTRUCTIVE TEST: #sudo DISK=/dev/sdb fio perf.ini
Jobs: 4 (f=4): [W(4)] [48.6% done] [0KB/423.9MB/0KB /s] [0/108K/0 iops]
[eta 00m:18s]

good.

# rand 4k write
# # set readwrite=randwrite
# DESTRUCTIVE TEST: #sudo DISK=/dev/sdb fio perf.ini
Jobs: 4 (f=4): [w(4)] [31.4% done] [0KB/319.7MB/0KB /s] [0/81.9K/0 iops]
[eta 00m:24s]

~80,000 IOPS, which is what the spec says,
http://www.crucial.com/usa/en/storage-ssd-m500

OK, lets put a filesystem on and see the difference

sudo mkfs.ext4 /dev/sdb
mkdir /tmp/scratch
sudo mount /dev/sdb /tmp/scratch

# These tests are non-destructive, we're writing to a file hosted by the
filesystem

# rand 4k write on ext4
# add size=10g to the job description (its more than we need but I don't
care, quick example)
# sudo DISK=/tmp/scratch/randwrite-ext4.out fio perf.ini

Jobs: 4 (f=4): [w(4)] [45.7% done] [0KB/215.2MB/0KB /s] [0/55.8K/0 iops]
[eta 00m:19s]

So there goes a third of my performance :/

But this isn't a typical workload. A 70% read 30% write mix is more typical.

# set readwrite=randrw
# set rwmixread=70
#
# sudo mkfs.ext4 /dev/sdb
# mkdir /tmp/scratch
# sudo mount /dev/sdb /tmp/scratch
fio-job-11: (g=0): rw=randrw, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio,
iodepth=32
Jobs: 4 (f=4): [m(4)] [20.0% done] [235.6MB/101.4MB/0KB /s] [60.3K/25.1K/0
iops] [eta 00m:Jobs: 4 (f=4): [m(

85K total IOPS with ~2/3 going to reads. reasonable.

Let's compare that again to block-io performance, same mix.

# sudo umount /tmp/scratch
# DESTRUCTIVE TEST: #sudo DISK=/dev/sdb fio perf.ini

Jobs: 4 (f=4): [m(4)] [20.0% done] [202.2MB/88128KB/0KB /s] [51.8K/22.4K/0
iops] [eta 00m:Jobs: 4 (f=4): [m(

the drop in read performance is probably  because I don't have any vfs page
cache help. my ssd might need to be
wiped too.

So that should give you an idea as to what to expect from your device.
Before you ask, I don't have an opinion
on which fs you should use for SSDs.

If you continue to see slowness once you've eliminated the video driver.
Use iotop  to
see which apps are touching your disk, maybe something is running away.
Also make sure the os isn't
doing something stupid like putting your link to sleep to save power,
powertop can help with this.

Hope this helps.

Peter


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