Re: [gentoo-user] Re: aligning SSD partitions

[Dale]

Nicolas Sebrecht wrote:
> The 06/09/12, Dale wrote:
>
>> But this is what you guys are missing too.  If you want to use tmpfs,
>> you have to have enough ram to begin with.  Whether you use tmpfs or
>> not, you have to have enough ram to do the compile otherwise you start
>> using swap or it just crashes.  Having ram is a prerequisite to using
>> tmpfs.
> This is too minimal overview to get the point. Memory is not a static
> place. This is not a cake beeing shared once. Memory is living. See my
> other mail.

I understand that memory is static but that is NOT what I was testing or
others either.  The test it whether putting portage's work directory on
tmpfs makes emerges faster not whether emerge using memory itself makes
it faster.  Since when you run emerge it loads everything into ram,
regardless of whether portages work directory is on tmpfs or not, it
doesn't matter.  This test is NOT about portage loading things into ram
WHILE emerging, it was about having the work directory on tmpfs and
speed.  Since emerge loads everything right after you hit the enter key,
it doesn't matter where the work directory is located. 

We wanted to change only one thing for this test, where portage's work
directory was.  It was not about how much ram a system has but where
tmpfs was located.  To use tmpfs, the system has to have enough ram to
begin with so systems that do not have larger amounts of ram were not
even relevant to the question.  If a system has small amounts of ram,
then most likely they can't use tmpfs anyway. 

>> There is another flaw in your assumption above.  I already had the
>> tarballs downloaded BEFORE even the first emerge.
> This is not a flaw in assumption. This is negligible.

It can make a huge difference.  The download times are included in the
emerge times if it is not already in distfiles.  So, if a tarball takes
a hour to download, it adds one hour to the emerge time.  Depending on
internet speed, it can be more than negligible.  I have DSL but it is
the slower package so this can in some cases make a HUGE difference
here.  Since I was running my tests here, I know it makes a difference
but you assumed it didn't.  That would be incorrect.  It does make a
difference and it can be a big one depending on the tarball size.

>
>> What the people wanted to test is if putting portages work directory on
>> tmpfs would make emerge times faster.
> Come'on. We all understood your goal from the beginning.

Well great.  We, and I, were only testing one thing not two or three
things.  We just wanted to change one setting, not disable a whole bunch
of stuff. 


>
>> Do we all admit that having portage on tmpfs does not make emerge times
>> faster yet?
> No. It depends on factors and underlying processes you claim they don't
> matter, which is wrong. They *might* be not relevant in some cases.
>

Actually, they don't matter on my system and since others got the same
results, it doesn't matter.  Again, we only wanted to change one
specific setting, tmpfs, nothing else.  That was the only thing we were
testing and it was the only thing I tested here and it is the only
results I am reporting.  I'm not reporting on how well emerge is using
ram after the command is given. 

So, accept it or not, it makes no difference whether portage's work
directory is on tmpfs or not speed wise.  You get the same results
either way.  In the case of the OP of this thread, it would likely be a
good idea if he can but he should not expect emerge to be any faster. 

Dale

:-)  :-) 

-- 
I am only responsible for what I said ... Not for what you understood or how you interpreted my words!