Le 05/06/2016 17:24, emninger@??? a écrit :
> Am Sun, 05 Jun 2016 12:00:01 +0000
> schrieb Didier Kryn <kryn@???>:
>
>> I have a laptop with 16GB of ram. I configured it like this with
>> the primary goal of not using swap at all. And my /tmp is a tmpfs
>> with a 4G limit. This allows me to use an SSD as hard disk drive. I
>> didn't want to swap to an SSD.
>>
>> I have never been short of ram in 3 years. I have compiled
>> kernels, GCC, and many other things on this laptop, runing make with
>> multiple threads; I sometimes got stuck by lack of cpu, never by lack
>> of ram.
>>
>> I understand that you want to go further and increase the size
>> of your /tmp by compressing it. It seems pretty complicated and
>> probably not worth the burden.
> Thank you Didier! Would you mind to put your exact configuration here?
------------- Begin of configuration ------------
HP EliteBook
4 cores Intel(R) Core(TM) i7-3687U CPU @ 2.10GHz
16GB RAM
SSD disk 256GB
fstab:
# <file system> <mount point> <type> <options>
<dump><pass>
# / was on /dev/sda5 during installation
UUID=d91acaa3-5fdc-49e9-9f2b-ba7f3efb33f9 / btrfs noatime
0 1
# /home was on /dev/sda10 during installation
UUID=4709a8c2-825d-43fc-83bb-3b7404feb4aa /home btrfs
noatime 0 2
# /usr was on /dev/sda6 during installation
UUID=05f9f811-b8b1-445f-ac8c-9537a202a9f9 /usr btrfs
noatime 0 2
# /var was on /dev/sda7 during installation
UUID=905a0998-c7fc-4544-a73e-44d8d803602c /var reiserfs
notail,noatime,nosuid 0 2
tmp /tmp tmpfs
size=4G 0 0
My fstab is a mess. I used several partitions not mentionned above
as chroots. I know it's an error to dispatch the OS into several
partitions when using btrfs; won't do it next time.
--------------- End of configuration ------------
> Anyway, i went a bit further and around the compressed ram theme.
> Given, that i probably will keep the harddrive swap partition
> (as i said: for hibernation/s2disk) would it be more useful to use
> zswap instead (zswap needs a physical swap device)? And to set the
> percentage of ram given to zswap pretty high? (Activate zswap would be
> some lines in the bootloader).
I haven't any partition formatted as swap, and, nevertheless,
hibernation works. I realize this just when writing this email and I now
wonder where the hell the kernel saves the system image!
>
> So, using tmpfs as parazyd pointed out, would go to be swapped early
> into the compressed swap in ram, when there is no more uncompressed ram
> available. Or is it ingenuous thinking?
>
> If i understand correctly, zswap will, when it really comes to the
> limits swap out the oldest swap pages to the "pysical" swap device,
> zram would kill them (?).
I guess you can swap to both zram and disk. swapon allows you to
give priorities, meaning swap could go to disk only when zram is full.
I would first try to estimate the real need for swap. The common
practice, for years, was to use a swap partition twice the size of the
RAM. Since today a typical RAM is around 4GB, this puts a limit of 12GB
total. But you've got 16! Without swap, you have more than a typical
laptop with swap.
Didier
::
Re: [DNG] use zram for /tmp - how?
