Udit, On Thu, May 17, 2018 at 9:13 AM, Udit agarwal <dev.mada...@gmail.com> wrote: > Hi all, > I was looking at the internal working of a benchmark and the way it disables > cache for direct IO operations, needed to benchmark storage device drivers. > I have a small query regarding how cache is organized in RTEMS: > > Usually data transfer model is something like: > Application address space --> Page cache --> Write-back cache --> storage > device > is this model valid for RTEMS too? > > Moreover, in FreeBSD/Linux, O_DIRECT flag is used with the file descriptor > to bypass write-back cache. do we have something like that in RTEMS? AFAIK, > In RTEMS, libblock is used to transfer data to the storage device. So, > configuring it like: >> >> #define CONFIGURE_BDBUF_MAX_READ_AHEAD_BLOCKS 0 > > should disable the cache? or is there any other setting that should be > tweaked? >
I think you are on the right path. We have bdbuf cache as the way to buffer block I/O operations. I don't know if that option is enough to turn off caching. You should check the user manual, and inspect the code. > Regards, > Udit > > > _______________________________________________ > devel mailing list > devel@rtems.org > http://lists.rtems.org/mailman/listinfo/devel _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
