[Disksim-users] The Disk's " Rotation speed (in rpms)" parameter value in the source code!

[Anjo Vahldiek]

Hi,

The struct you are looking for is called dm_mech_g1 in 
diskmodel/mech_g1.h. It stores the rpm and the rpmerror. If you look at 
when rpm is used you will find it in mech_g1_load.c (dm_mech_g1_load 
function). It is used to calculate the rotatetime variable of 
dm_mech_g1. This variable is used in various places in mech_g1.c e.g. 
dm_rottime_g1.

To me it seems that instead of changing the rpm you should rather 
change the rotatetime, since the rpm is only used during load to 
compute the rotatetime... You should be able to access the structure 
through the dm_disk_if struct in disk.

Hope this helps,
Anjo

On Mon 01 Aug 2011 11:39:27 AM CEST, Peyman Behzadnia wrote:
> Dear all,
> I have a question regarding the source code of the disksim. I'd be 
> grateful if anybody has any hint or comment about it.
>   For my current research simulation, i'm in need of dynamically 
> changing the rotation speed of some disks during the simulation for 
> power-saving purposes. In other words, the value of rotation speed 
> parameter of the disk mechanical model should be changed after a 
> particular elapsed time. For this goal, i have to figure out where this 
> parameter value of each disk is stored in the code and how this 
> parameter is loaded and used for rotational latency calculation.
> I found out that the main information is in the disksim_diskctlr.c 
> (mainly in the lines 4105-4111) for calculating the rotational latency 
> of each request. However, i have not figured out yet where exactly the 
> rpm value of each disk is stored in order to manipulate it. Has anybody 
> else done something similar to this? any clue?
> Thanks
> Best,
> Peyman
> 
> 
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