[indiana-discuss] [caiman-discuss] Followup: Copy-on-write compressed ramdisk

[Moinak Ghosh]

On Tue, Jan 6, 2009 at 2:28 AM, Dave Miner <dminer at opensolaris.org> wrote:
> Moinak Ghosh wrote:
>>
>> Hi,
>>
>>   So I got a working solution now and got a successful livecd boot off
>> a lofi-compressed ramdisk. This solution satifies various requirements
>> even for normal harddisk boot and avoids the need for multiple different
>> solutions. More details here:
>>
>> http://moinakg.wordpress.com/2009/01/01/reducing-opensolaris-ramdisk-greed/
>>
>
> This is quite cool, Moinak.  Out of curiosity, what's the difference in:
>
> - memory usage

   Memory usage while booting is no worse than the existing mechanism
   that gzip compresses the files inside boot archive. This memory gets
   eventually freed.

   Memory usage while running initially the same as the compressed size.
   In BeleniX 0.7.1 82MB ramdisk gets compressed to 29MB. Once writes
   happen the size grows maybe a couple of MBs. I have to add a variable
   to track actual usage and enhance ramdiskadm output to print it.
   Size growth is not unbounded however. The maximum growth is limited
   by the maximum size and free space that the filesystem was configured
   with. For eg. in an 82MB ramdisk if 4MB is free then UFS knows of that
   and will only allow 4MB more writes to happen. So runtime size will be
   limited to 29 + 4 = 33MB.

> - load time for the ramdisk from GRUB

   Couple of seconds in VirtualBox. The "modulenounzip" GRUB directive
   has to be used so that GRUB does not attempt to uncompress it.

>
> I'll certainly play with this when I get some time.  Thanks!
>
> Dave
>

Regards,
Moinak.
-- 
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