On 31/08/16 14:14, Alexey Kardashevskiy wrote: > On 14/07/16 14:25, Balbir Singh wrote: >> >> From: Balbir Singh <bsingharora@xxxxxxxxx> >> Subject: [RESEND][v2][PATCH] KVM: PPC: Book3S HV: Migrate pinned pages out of CMA >> >> When PCI Device pass-through is enabled via VFIO, KVM-PPC will >> pin pages using get_user_pages_fast(). One of the downsides of >> the pinning is that the page could be in CMA region. The CMA >> region is used for other allocations like the hash page table. >> Ideally we want the pinned pages to be from non CMA region. >> >> This patch (currently only for KVM PPC with VFIO) forcefully >> migrates the pages out (huge pages are omitted for the moment). >> There are more efficient ways of doing this, but that might >> be elaborate and might impact a larger audience beyond just >> the kvm ppc implementation. >> >> The magic is in new_iommu_non_cma_page() which allocates the >> new page from a non CMA region. >> >> I've tested the patches lightly at my end, but there might be bugs >> For example if after lru_add_drain(), the page is not isolated >> is this a BUG? >> >> Previous discussion was at >> http://permalink.gmane.org/gmane.linux.kernel.mm/136738 >> >> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> >> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> >> Cc: Paul Mackerras <paulus@xxxxxxxxxx> >> Cc: Alexey Kardashevskiy <aik@xxxxxxxxx> >> >> Signed-off-by: Balbir Singh <bsingharora@xxxxxxxxx> > > > > Acked-by: Alexey Kardashevskiy <aik@xxxxxxxxx> > Thanks! I tested this patch against latest mainline and here are the test results System RAM - 64GB VM instance 1 - size 55GB Before patch - nr_free_cma after launch 8900 After patch - nr_free_cma after launch 39500 Balbir Singh. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>