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

[Dale <rdalek1967@gmail.com>]

Michael Mol wrote:
> On Thu, Sep 6, 2012 at 10:20 AM, Dale <rdalek1967@gmail.com> wrote:
>> Nicolas Sebrecht wrote:
>>> The 06/09/12, Dale wrote:
>>>
>>>> Not quite.  The theory is that if you put portages work directory on
>>>> tmpfs, then all the writes and such are done in ram which is faster.
>>> No! This is too much simplistic view to explain what you see.
>>>
>>> In practice, _all_ the writes always happen in RAM whatever backend
>>> storage you use.
>>>
>>> The difference you could see is if there is not enough RAM for the
>>> kernel cache, it will have to wait for the backend storage.
>>>
>>
>> OK.  Step by step here so hopefully you and Neil can follow.
>>
>> Freshly booted system.
>> Clear caches just to be sure
>>
>> emerge foo with portages work directory on tmpfs
>> clear caches again
>> emerge foo with portages work directory on disk
>> clear caches again.
>> emerge foo with portages work directory on tmpfs
>> clear caches again
>> emerge foo with portages work directory on disk
>>
>> You repeat this enough times and you see that it doesn't matter if
>> portage's work directory is on disk or on tmpfs.
> If you have enough RAM, then this is certainly true. Nobody is
> disputing that. They've been trying to explain that there's a
> difference when you _don't_ have that much RAM, and they've been
> trying to explain the mechanism behind that.
>
>

But, if you don't have enough ram to compile a package, then you can't
use tmpfs anyway.  So, that point is not really a point.  If you try to
compile OOo on a machine with 512M of ram, you can't use tmpfs because
you don't have enough ram to even consider it.  The amount of ram wasn't
what I was testing, I was testing whether using tmpfs makes it faster
regardless of the amount of ram.  It doesn't.  Once everything related
to that specific emerge process is loaded, tmpfs doesn't matter.  That
is what I been saying this whole time. 

Dale

:-)  :-) 

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