Several questions about L2 Cache (and suggestion)

[RobF99]

Some questions for support....

1. Gather interval.... what is the difference between Default and Idle? I see in some previous posts that Default does not gather when Windows is busy and therefore it seems the same as Idle based upon this description. Can you please clarify.

2. If the data that is to be gathered for L2 cache is either in L1 cache or Windows cache does the program gather the data from the data in memory or is there no way that this data can be referenced to blocks on the hard drive? If there was a way to map such data this would make L2 gather have much less overhead impact on performance if one sets a low number for gather interval and data can go from L1 or Windows cache to L2 (much faster) instead of reading from the hard drive.

3. Suggestion.... I process huge amounts of imagery and sometimes my applications will run for 10 hours and process up to 1 Tb data at the time. My 512 Gb SSD has 330 Gb allocated for L2 cache. With default gather interval the system is never free to populate L2 cache. When my applications are done I see that L2 cache gathering commences.... the problem is that is reads ALL of the 1 Tb of data and this can take several hours AND it also unnecessarily writes to the SSD for data that will be evicted later on since it will most likely only keep the last 330 Gb of gathered data. It would be really nice if the program could determine that this will happen and ignore the first 670 Gb of data and only L2Storage Write the ACTUAL data that will be kept in L2 cache by the time the L2 gather will be complete. Does that make sense? It would simulate the L2 gather interval in memory before committing and only reading and L2 gathering the data that will actually remain in L2.

4. Data in L2 Cache.... is the data evicted First In First Out or is data kept in L2 cache actually based upon frequency of use of the data with most often used data being least likely to be evicted when cache is full?

Thanks

[Support]

1. Gather interval.... what is the difference between Default and Idle? I see in some previous posts that Default does not gather when Windows is busy and therefore it seems the same as Idle based upon this description. Can you please clarify.

Default: gather few data every 30 seconds even when Windows is busy. Of course, when Windows is idle, gather data as much as possible.
Idle: gather data only when Windows is idle.

2. If the data that is to be gathered for L2 cache is either in L1 cache or Windows cache does the program gather the data from the data in memory or is there no way that this data can be referenced to blocks on the hard drive?

Will gather data from L1. But cannot from Windows cache.

It would be really nice if the program could determine that this will happen and ignore the first 670 Gb of data and only L2Storage Write the ACTUAL data that will be kept in L2 cache by the time the L2 gather will be complete. Does that make sense?

Yes, we do have the plan to improve the program for such cases. However, it is not so easy as expected, as we also have to consider the cache replace algorithm. Anyway, we'll try to work it out in future.

4. Data in L2 Cache.... is the data evicted First In First Out or is data kept in L2 cache actually based upon frequency of use of the data with most often used data being least likely to be evicted when cache is full?

Close to FRU, with other tuning algorithms.

[RobF99]

Thank you for your reply.

Can I ask also.... is IDLE for when Windows/CPU is idle or hard drive is idle?

[Support]

Mainly hard drive is idle