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Altera_Forum
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16 years ago

copy performance in user space vs. kernel

Hi, I am using Linux 2.6.32 with MMU with DDR SDRAM and I've run into some performance issues copying data. Copying from DDR to DDR using memcpy in an application only gets me 6-10MB/s. Copyi...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

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Measurements are done by putting out a signal on a GPIO pin (tp)

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As in User mode I/O devices can't be accessed directly, are you sure that the setting of the I/O bit does not result in an exception, a switch to Kernel mode and back and thus slows down the process ?

Testing with several different buffer sizes should make this clear. Moreover cache issues might play some role, here.

-Michael