Jacques Montier writes:

I bought a 250Go SSD M4 Crucial , read (of course) Gentoo documentation
and installed the drive on my desktop pc (Asus MB, Intel ie7 and 6Go RAM).

1- Everything seems to work perfectly, but i would like to know if my
configuration is ok or could be optimized.

/tmp and /var/log are on tmpfs

Like Volker said. Yikes! Or is that just a typo and you meant /var/tmp? Still, I would prefer to have that on the HDD.

/boot, / and /var are on SSD (sda),
swap, /home, /usr/portage, /var/tmp and /var/log on a 1To SATA HDD (sdb)

I would put the portage tree on the SDD.

        Wonko