On 06.02.20 20:15, Michael Hinton wrote: > Hi Jan, > > On Thursday, February 6, 2020 at 12:06:05 PM UTC-7, Jan Kiszka wrote: > > On 06.02.20 20:00, Michael Hinton wrote: > > map_range((char *)MGH_HEAP_BASE, MGH_HEAP_SIZE, MAP_UNCACHED); > > Why are you mapping your RAM uncached? That's (roughly) only needed for > MMIO. > > I guess I was copying the other map_range() call used to set up the > IVSHMEM from the ivshmem demo. So I have no particular reason.
The ivshmem demo is doing that only for the MMIO register region, not the shared memory is later maps. > > I see that it sets the PG_PCD argument to the page table entry in > map_range(). What does that do? That controls caching on page-level granularity. > > Should I set it to MAP_UNCACHED and see if that helps with performance? MAP_CACHED. When it's uncached, every memory access will hit the RAM. That is... not very fast. Jan -- Siemens AG, Corporate Technology, CT RDA IOT SES-DE Corporate Competence Center Embedded Linux -- You received this message because you are subscribed to the Google Groups "Jailhouse" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/jailhouse-dev/8e62e937-be43-4c10-721c-78f2b11a5eb1%40siemens.com.
