On Mon, Mar 17, 2025 at 03:44:17PM -0600, Alex Williamson wrote: > On Wed, 12 Mar 2025 15:52:55 -0700 > > @@ -679,6 +679,7 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr, > > > > if (unlikely(disable_hugepages)) > > break; > > + cond_resched(); > > } > > > > out: > > Hey Keith, is this still necessary with: > > https://lore.kernel.org/all/20250218222209.1382449-1-alex.williamson@xxxxxxxxxx/ Thank you for the suggestion. I'll try to fold this into a build, and see what happens. But from what I can tell, I'm not sure it will help. We're simply not getting large folios in this path and dealing with individual pages. Though it is a large contiguous range (~60GB, not necessarily aligned). Shoould we expect to only be dealing with PUD and PMD levels with these kinds of mappings? > This is currently in linux-next from the vfio next branch and should > pretty much eliminate any stalls related to DMA mapping MMIO BARs. > Also the code here has been refactored in next, so this doesn't apply > anyway, and if there is a resched still needed, this location would > only affect DMA mapping of memory, not device BARs. Thanks, Thanks for the head's up. Regardless, it doesn't look like bad place to cond_resched(), but may not trigger any cpu stall indicator outside this vfio fault path.
