FreeBSD and Linux SSD Write Speeds

[Valeri Galtsev]

On Wed, June 21, 2017 1:33 pm, Tim Daneliuk wrote:
> On 06/21/2017 11:27 AM, Valeri Galtsev wrote:
>> sync; date; dd if=/dev/zero of=foo bs=8M count=512; sync; date
>
> So I just did this:
>
>    sync; date; dd if=/dev/zero of=foo bs=8M count=1024; sync; date
>
> And got this:
>
> Linux:
>
> Wed Jun 21 13:30:22 CDT 2017
> 1024+0 records in
> 1024+0 records out
> 8589934592 bytes (8.6 GB, 8.0 GiB) copied, 33.523 s, 256 MB/s
> Wed Jun 21 13:30:57 CDT 2017
>
>
> FreeBSD:
>
> Wed Jun 21 13:28:23 CDT 2017
> 1024+0 records in
> 1024+0 records out
> 8589934592 bytes transferred in 46.508336 secs (184696666 bytes/sec)
> Wed Jun 21 13:29:10 CDT 2017
>
> So ... still a pretty big disparity

It is.

>
> I don't want to test against a raw device or partition because that's
> not how these systems get used.  My FreeBSD FS is UFS and maybe that
> simply is not as efficient on an SSD as ext4.

OK, at least it is not zfs on FreeBSD: zfs has its reasons to be slower.
As others mentioned, it can be one or more of: particular two devices
performance difference; less than optimal parameters of UFS; UFS itself
being not that "shiny" compared ext4 ( I somehow discount the difference
in scheduler, process switching, etc...)

Oh, well... I feel like devoting some time to experimenting too: curiosity
;-)

Valeri

>
> This isn't a big deal, just an eyebrow raiser for me.  I've used FreeBSD
> as a production OS since 2.x and have always found it to be consistently
> quicker and have a smaller footprint than Linux.  This was just a
> surprise.
>
> --
> ----------------------------------------------------------------------------
> Tim Daneliuk     tundra at tundraware.com
> PGP Key:         http://www.tundraware.com/PGP/
>
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++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++