On 02/06/13 00:16, Jonathan Marsden wrote:
On 06/01/2013 03:30 PM, Yorvyk wrote:
I've not found any down sides to zRAM with more than 512 MiB of
RAM. Below that, especially with CPUs below 1GHz, there are
frequent pauses as memory gets swapped about when the zRAM
allocation has been used up and swap starts using the disk
partition/file. Above 2GiB of RAM zRAM doesn't appear to have much
effect.
And this is the problem... when you *really* need it, on older slower
PCs with little RAM, zRAM doesn't work as smoothly as some seem to be
suggesting. Using it on a 2GB Lubuntu machine seems somewhat
pointless... you already have enough RAM for most normal desktop
usage purposes in that case.
My sense is that zRAM probably helps most in a fairly small set of
machines that have decent CPUs *and* limited RAM... maybe 1.5GHz to
2GHz dual core CPUs and 512MB to 1GB of RAM? But I don't think that
is all that common, and such machines can often add more RAM, which
is the right way to prolong their usefulness, I think.
From the experiences of people I know and my own, along with anecdotal
evidence from around the web seems to confirm this.
Adjusting swappiness down to 10 or 20 also causes similar effects
to above on really low resource machines.
And those effects do not happen with a default install? That's a bit
surprising... Once a machine needs more RAM than is physically
present, you *are* going to get swapping and the related delays.
But lowering swappiness should not (I'd think!) make that issue
worse.
Some where on the kernel mailing list (I think) is an explanation of
this phenomenon, along with a very log discussion/argument about the
best default swappiness setting. If my memory serves me right, the
problem with the pregnant pauses at, say 10, is because the kernel tends
to move quite large chunks about. With the default setting of 60 the
data tends to trickle in and out.
Which are the exact machines that a "fix" for lack of RAM is needed
on.
Overall, I think we do better to leave things as they are, and
document use of zRAM and swappiness changes as things for the
enterprising enthusiast to try out if they wish to. That way, we do
not accidentally make things worse for the majority who either have
enough RAM already, or are willing to tolerate swapping because they
know they lack sufficient RAM.
Note: A default browser that uses less RAM for common use cases *is*
a really good idea for Lubuntu, all other things being equal.
Trying to be more expert than the kernel maintainers about swapping
and RAM usage may not be such a great idea, IMO.
Let's pick a good default browser. Let's not mess with swappiness or
zRAM-by-default.
Jonathan
--
Steve
--
Lubuntu-users mailing list
[email protected]
Modify settings or unsubscribe at:
https://lists.ubuntu.com/mailman/listinfo/lubuntu-users
