Re: [gentoo-amd64] Re: tmpfs help

[Beso]

2008/2/13, Duncan <1i5t5.duncan@×××.net>:
>
> Volker Armin Hemmann <volker.armin.hemmann@××××××××××××.de> posted
> 200802131346.26316.volker.armin.hemmann@××××××××××××.de, excerpted below,
> on  Wed, 13 Feb 2008 13:46:26 +0100:
>
> > On Mittwoch, 13. Februar 2008, Duncan wrote:
> >>>removed lots of irrelevant 'my hardware is so cool' stuff'.
> >
> > You forget some (little) things. Not everything can be swapped out. Swap
> > is extremly slow AND it is much worse to swapout/swapin programm code
> > that should be run, instead of fetching some files from disk while the
> > programm runs.
>
> It's not always much worse, because as I explained, in my case, swap is 4-
> way striped while most of the main system is only two-way striped.  Thus,
> that "irrelevant" stuff is relevant after all, because it alters the
> conditions of the case in debate, because swap reads in at ~2x the speed
> of most data read off disk including apps (which is itself ~2x what a
> single-disk system might reasonably expect).
>
> I've a feeling not appreciating this, not appreciating that your "test"
> case example of compiling with 2 gigs RAM vs only 1 has little to do with
> what might occur with PORTAGE_TMPDIR on tmpfs vs on disk, and not
> appreciating the point RF and I are both trying to make, is due to the
> same logic flaw.


well, for now, the fact for me are:
1. no ram upgrade is good -> notebook ram costs much more than desktop one
and the notebook itself has a limit
2. small packages, that have much update during the single days of the week
(i do sync once a day) get compiled at least 2-3 times faster than normal
compilation into disk space
3. big packages that usually compile in 30-40 mins now compile in about
10minutes or so faster. to see how it feels to use tmpfs for compilation i
have to upgrade kde. usually kde3 would build into 2 days of about 13 hours
compilation time each. i'll have to see how fast would kde4 build.
4. the sync now takes less than 2mins while normally it would take about
10mins.
i'll try out duncan's speedups for shm and but for the dev one i don't use
baselayout 2 and i'm still with the 1st version, since i don't feel like
upgrading to it yet. but i'd like to know some more about what are the
improvements of the second version.
5. as for the raid stuff i cannot do it since i've only got one disk. i'll
try to see what happens with swap set to 100.
6. if i use some other programs while compiling into tmpfs bigones i need to
nice the process or i'll get some misbehaviour from the other programs.

-- 
dott. ing. beso