Mailinglist Archive: opensuse (933 mails)

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Re: [opensuse] openSUSE on SSD?
  • From: Greg Freemyer <greg.freemyer@xxxxxxxxx>
  • Date: Tue, 1 Jun 2010 17:37:10 -0400
  • Message-id: <AANLkTinz0biZzaEhY6rPCYCuLLL8wiw000L2vyGTrUeQ@xxxxxxxxxxxxxx>
On Tue, Jun 1, 2010 at 3:59 PM, Jan Ritzerfeld
<suse@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Am Dienstag, 1. Juni 2010 schrieb Greg Freemyer:

[...].
Mounting with relatime has been the Linux kernel and Opensuse default
for a year or more.

I thought, laptop-mode-tools added this option for me.


No its a generic kernel thing I believe since 2.6.27 or so (ie. since
OS 11.1).

So if you call mount with no options, you now get "relatime" as I understand it.

And Ted's post you linked to says Mutt breaks if you simply switch to
noatime without in some way reconfiguring Mutt. (He doesn't provide
details as to how to fix Mutt.)

So, switching to noatime is not a zero risk proposition, especially
for the entire distro.

Why do you think noatime will significantly improve on relatime?

http://thunk.org/tytso/blog/2009/03/01/ssds-journaling-and-noatimerelatime/
| Unfortunately, relatime is not free. As you can see below, it has roughly
| double the overhead of noatime (but roughly half the overhead of using the
| standard Posix atime semantics):

Yes, but his conclusion includes:

===
the problem was that first generation SSD’s had a very bad problem
with what has been called the “write amplification effect”, where a 4k
write might cause a 128k region of the SSD to be erased and rewritten.
...
However, the next generation of SSD’s, such as Intel’s X25-M SSD, have
worked around the write amplification affect.
===

I personally think the first generation devices are just too slow to
be considered a performance boost for lots of reasons, so I will not
be buying one period.

As to the second generation devices which have been around for 18
months now I believe, they are much faster than rotating disk at
random i/o (Approx 15K io's / second), so using noatime with them is
much less of a boost than for rotating disk.

So if your not using noatime for rotating, why would you suddenly
consider it critical for SSD.

Greg
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