Best way to use zram in Fedora 21?

[Darren Steven]

I recall that multiple zram devices are due to the way the device is
handled - there's some need for multiple devices to allow multiple cores to
operate concurrently against it.

zswap looks interesting. compcache/zram used to be able to setup a  backing
store that worked like zswap, but was poor performing. I think that if you
wanted to eventually persist to disk, then zswap might be the way to go. If
you don't want (or don't have) hard swap, then zram.

On Fri Nov 28 2014 at 13:41:42 Corey Sheldon <sheldon.corey at gmail.com>
wrote:

> ok to the naming and multi zram devices questions:
>
>
> 1) one single large space is wasteful if you have your machine up for
> longer than a  single (or series ) of heavy lifting operations  --say you
> are rendering a video and then back to the usual grind stuff would you want
> all that extra space just wasted ?  also say a follow up process is in need
> of more would you wanna be stuck on previous values?   zram is dynamic in
> nature smaller more numerous /dev/zram$i  allows for that and in a dynamic
> manner...
>
>
> 2) it the RAM its based off not swap and the "z" is known as dynamic
>
>
> Corey W Sheldon
> Freelance IT Consultant, Multi-Discipline Tutor
> 310.909.7672
> www.facebook.com/1stclassmobileshine
>
> On Thu, Nov 27, 2014 at 7:39 PM, Reindl Harald <h.reindl at thelounge.net>
> wrote:
>
>>
>>
>> Am 28.11.2014 um 01:34 schrieb Zbigniew Jędrzejewski-Szmek:
>>
>>> On Fri, Nov 28, 2014 at 01:21:26AM +0100, Zbigniew Jędrzejewski-Szmek
>>> wrote:
>>>
>>>> On Thu, Nov 27, 2014 at 04:42:36PM +0100, Juan Orti wrote:
>>>>
>>>>> El 2014-11-27 14:48, Reindl Harald escribió:
>>>>>
>>>>>> Am 27.11.2014 um 14:25 schrieb Juan Orti:
>>>>>>
>>>>>>> Reindl, I'm of the opinion you should upload your scripts to some git
>>>>>>> repository and package them to be part of the distribution. I can
>>>>>>> co-maintain if you wish
>>>>>>>
>>>>>>
>>>>>> feel free to package it!
>>>>>>
>>>>>> that's why i attached it as i saw the topic
>>>>>> i am not a active packager on the Fedora infrastrcuture
>>>>>>
>>>>>
>>>>> Ok, I've uploaded the scripts to GitHub and submitted a review request:
>>>>>
>>>>> https://github.com/jorti/zram-swap
>>>>> https://bugzilla.redhat.com/show_bug.cgi?id=1168692
>>>>>
>>>> I have a question about the code: why are multiple swap devices needed?
>>>> /sys/block/zram0/max_comp_streams can be set to whatever number is
>>>> wanted. While it might be useful to have additional zram devices
>>>> for different purposes, I don't think more than one zram swap is
>>>> useful. If you only have one device, then reloading the module is
>>>> no longer necessary to change the parameters, since everything
>>>> else seems to be configurable through sysfs.
>>>>
>>> And another question (sorry, I never used compressed swap before):
>>> why not zswap? It seems to be a better fit for the desktop/server
>>> environments that Fedora is used for. IIUC, zswap is better because
>>> it overflows automatically into the backing swap device
>>>
>>
>> on machines with plenty RAM i prefer not have a swap partition or a swap
>> file at all - especially on virtual machines it's a waste of (possible
>> expensive SAN) disk storage
>>
>> on virtual servers currently i prefer zram inside the guest to avoid OOM
>> conditions in the guest while the memory compression of the hypervisor
>> steps in too late and is more for overcommit the host
>>
>>
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