• Aneesh Kumar K.V's avatar
    powerpc/mm: Don't send IPI to all cpus on THP updates · fa4531f7
    Aneesh Kumar K.V authored
    Now that we made sure that lockless walk of linux page table is mostly
    limitted to current task(current->mm->pgdir) we can update the THP
    update sequence to only send IPI to CPUs on which this task has run.
    This helps in reducing the IPI overload on systems with large number
    of CPUs.
    
    WRT kvm even though kvm is walking page table with vpc->arch.pgdir,
    it is done only on secondary CPUs and in that case we have primary CPU
    added to task's mm cpumask. Sending an IPI to primary will force the
    secondary to do a vm exit and hence this mm cpumask usage is safe
    here.
    
    WRT CAPI, we still end up walking linux page table with capi context
    MM. For now the pte lookup serialization sends an IPI to all CPUs in
    CPI is in use. We can further improve this by adding the CAPI
    interrupt handling CPU to task mm cpumask. That will be done in a
    later patch.
    Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    fa4531f7
pgtable-book3s64.c 5.11 KB