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Re: Summary: Moving /tmp to tmpfs makes it useless

2012/6/10 Wouter Verhelst wrote:

> Sorry, but this is a biased summary, and therefore useless for what it
> intends to be.

Yes, I know. It's biased toward the /tmp and real-world applications.

>> "/tmp on tmpfs is good" quotes
>> No real quotes here. Most of this and other threads were about why
>> /tmp on tmpfs is not that bad. But there're no real quotes explaining
>> why it's good.
> This is wrong. There were several (including by me). You dismissed them,
> not considering them valid, but that doesn't mean they are.

I dismissed everything that was not related to /tmp or some popular apps.

A lot of people (including you) said that tmpfs makes things faster. But
there were no examples of popular use-cases becoming faster because
of /tmp on tmpfs, so I had nothing to quote.

Nobody could provide examples or numbers of how much /tmp on tmpfs reduces
amount of writes, and tests showed that tmpfs+swap may even increase amount
of writes (hence not always good for SSD), tmpfs does not have 5% overflow
safety, it does not help to protect from symlink attack and its name is not
a reason to use it. :) (if I quoted "it's called *tmp*fs for a reason" in a
"tmpfs is good" section it would be looking like humiliation, imho)

If you need a tmpfs for your short builds you can mount it to /var/ram and
use it there. But it's not related to /tmp, so I dismissed that too. Yes,
tmpfs may be useful sometimes (and I even explained how to use it in
"Alternatives" section), but that's outside of the topic of this thread if
it's not about /tmp.

If you'd said something like "I put /tmp on tmpfs and my ethernet became
twice faster", or "Because of /tmp on tmpfs firefox loads pages 30% faster"
that would be a good thing to quote. Especially if you could provide some
details so that anybody could check it. :)

But there were no examples, just some theories. And I tried to avoid
theories because they may be wrong (I explained why some popular
theories are wrong in the Q/A section however).

> If you're going to post a thread summary, please do not filter out
> information you don't agree with. Otherwise you're not posting a thread
> summary, you're posting a 'my side of the fence' summary.

I had to filter it. Otherwise it would be a copy of entire thread. :)
Since the initial topic was not about tmpfs in general, but about /tmp
and real-world applications, I filtered almost everything that's not
related to it.

It does not mean that I don't agree with that information. For example
Stefan Lippers-Hollmann's test showed that kernel is building 15% faster
on ext4 than on tmpfs, but I had not included that in summary, because
people don't build their kernels in /tmp by default.

I'm not stupidly opposite to tmpfs even for corner cases. I.e. if we could
find that firefox works 30% faster with /tmp on tmpfs on PCs with >1GB RAM
and disks with <1GB free space then... we could write an initscript, that
checks for amount of RAM, free space and presence of firefox and mounts
tmpfs to /tmp if it makes things faster. But there were no such examples,
unfortunately. I could suggest a dozen of different solution, if only there
were a problem to solve.

Of course I could have missed some important examples about /tmp and real
applications. Sorry if I did and I would be glad if you point them out.


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