Originally Posted by TimHuey
Does anyone know if the workunits expire based on processor/system specs or just size of the work unit.
Assuming you are talking about a generic PC, this is/was the logic:
How do you set the deadlines for the work units?
Each work unit is benchmarked on a dedicated 2.8 GHz Pentium 4 machine with SSE2 disabled. For most work units (although there may be exceptions, described in the next paragraph), we apply this equation
timeout = 20 * (daysPerWU) + 2
deadline = max(30* (daysPerWU) + 2,10)
where daysPerWU is the number of days it took to complete the unit. The "+2" days is there to give an additional buffer for fast WUs (to allow for servers down, etc). If 30*daysPerWU is less than 10 days, we set the deadline to 10 days, as a minimum time for all projects. The timeout is the time at which the WU is resent to another client and the deadline is the last time which we will give stats credit for the WU.
For the PS3, the setting is specialized:
How long will it take to complete the work unit (WU)?
We have set PS3 WU's to take approximately 8 hours to complete. The logic behind this was to ensure that the PS3 could be run only over night and still yield a useful result. We will likely decrease this time in the future to try to make it easier for PS3 donors to only briefly run their machines, but still make useful contributions.
Occasionally, deadlines may be set shorter or longer than the above calculation indicates, but the reason for having deadlines at all is that the sooner we get back work units, the sooner we can put the results to good use. Also, different projects have different requirements server-side and may require shorter or allow longer deadlines (eg "pfold" calculations can often be run without any deadlines, whereas MREMD calculations work best with very tight deadlines). The assignment server does take machine performance into account in making assignments, thereby allowing slower machines to receive more appropriate work units.