Forum Discussion
Altera_Forum
Honored Contributor
Honored ContributorMax throughput of SOPC DMA?
Hello, Currently I have a system with DMA transfers and DDR2 SDRAM (and a lot of other stuff). I'm using the normal SOPC builder DMA controller. I run the system on 100 MHz, the DDR2 SDRAM run...
Altera_ForumHonored Contributor
Honored ContributorAnd here's the final table for those who would like to know, before I strip the whole thing down again and add scatter-gather DMAs :).
Transferring 195.3125 megabytes. On-chip memory uses bursts of 1024 words. DDR2 memory uses bursts of 256 words. --Performance Counter Report-- +---------------+-----------+---------------+-----------+ | Section | Time (sec)| Time (clocks)|Occurrences| +---------------+-----------+---------------+-----------+ |DDR2<->DDR2 | 6.40292| 640292166| 1| +---------------+-----------+---------------+-----------+ |DDR<->SRIO | 6.75203| 675203128| 1| +---------------+-----------+---------------+-----------+ |OC->SRIO->OC | 2.72834| 272833895| 1| +---------------+-----------+---------------+-----------+ |OC<->OC | 2.69376| 269375544| 1| +---------------+-----------+---------------+-----------+ 1. Transfer speed: 195.3125 / 6.40292 = 30.5037 megabyte/second 2. Transfer speed: 195.3125 / 6.75203 = 28.9265 megabyte/second 3. Transfer speed: 195.3125 / 2.72834 = 71.5866 megabyte/second 4. Transfer speed: 195.3125 / 2.69376 = 72.5055 megabyte/second Reasons the DDR2 is much slower are: only 256 word bursts, clock crossing bridge and probably bus width adapters.
