| Message ID | 20190923213022.7740-1-leonardo@linux.ibm.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [1/1] powerpc: kvm: Reduce calls to get current->mm by storing the value locally | expand |
I have done a very simple comparison with gdb disassemble: By applying this patch, there was a reduction in the function size from 882 to 878 instructions. (It's a resend, due to not having all the correct lists on my previous mail) On Mon, 2019-09-23 at 18:30 -0300, Leonardo Bras wrote: > Reduces the number of calls to get_current() in order to get the value of > current->mm by doing it once and storing the value, since it is not > supposed to change inside the same process). > > Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> > --- > Re-sending to all lists involved. (I missed kvm ones) > > arch/powerpc/kvm/book3s_64_mmu_hv.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c > index 9a75f0e1933b..f2b9aea43216 100644 > --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c > +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c > @@ -508,6 +508,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, > struct vm_area_struct *vma; > unsigned long rcbits; > long mmio_update; > + struct mm_struct *mm; > > if (kvm_is_radix(kvm)) > return kvmppc_book3s_radix_page_fault(run, vcpu, ea, dsisr); > @@ -584,6 +585,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, > is_ci = false; > pfn = 0; > page = NULL; > + mm = current->mm; > pte_size = PAGE_SIZE; > writing = (dsisr & DSISR_ISSTORE) != 0; > /* If writing != 0, then the HPTE must allow writing, if we get here */ > @@ -592,8 +594,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, > npages = get_user_pages_fast(hva, 1, writing ? FOLL_WRITE : 0, pages); > if (npages < 1) { > /* Check if it's an I/O mapping */ > - down_read(¤t->mm->mmap_sem); > - vma = find_vma(current->mm, hva); > + down_read(&mm->mmap_sem); > + vma = find_vma(mm, hva); > if (vma && vma->vm_start <= hva && hva + psize <= vma->vm_end && > (vma->vm_flags & VM_PFNMAP)) { > pfn = vma->vm_pgoff + > @@ -602,7 +604,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, > is_ci = pte_ci(__pte((pgprot_val(vma->vm_page_prot)))); > write_ok = vma->vm_flags & VM_WRITE; > } > - up_read(¤t->mm->mmap_sem); > + up_read(&mm->mmap_sem); > if (!pfn) > goto out_put; > } else { > @@ -621,8 +623,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, > * hugepage split and collapse. > */ > local_irq_save(flags); > - ptep = find_current_mm_pte(current->mm->pgd, > - hva, NULL, NULL); > + ptep = find_current_mm_pte(mm->pgd, hva, NULL, NULL); > if (ptep) { > pte = kvmppc_read_update_linux_pte(ptep, 1); > if (__pte_write(pte))
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 9a75f0e1933b..f2b9aea43216 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -508,6 +508,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, struct vm_area_struct *vma; unsigned long rcbits; long mmio_update; + struct mm_struct *mm; if (kvm_is_radix(kvm)) return kvmppc_book3s_radix_page_fault(run, vcpu, ea, dsisr); @@ -584,6 +585,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, is_ci = false; pfn = 0; page = NULL; + mm = current->mm; pte_size = PAGE_SIZE; writing = (dsisr & DSISR_ISSTORE) != 0; /* If writing != 0, then the HPTE must allow writing, if we get here */ @@ -592,8 +594,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, npages = get_user_pages_fast(hva, 1, writing ? FOLL_WRITE : 0, pages); if (npages < 1) { /* Check if it's an I/O mapping */ - down_read(¤t->mm->mmap_sem); - vma = find_vma(current->mm, hva); + down_read(&mm->mmap_sem); + vma = find_vma(mm, hva); if (vma && vma->vm_start <= hva && hva + psize <= vma->vm_end && (vma->vm_flags & VM_PFNMAP)) { pfn = vma->vm_pgoff + @@ -602,7 +604,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, is_ci = pte_ci(__pte((pgprot_val(vma->vm_page_prot)))); write_ok = vma->vm_flags & VM_WRITE; } - up_read(¤t->mm->mmap_sem); + up_read(&mm->mmap_sem); if (!pfn) goto out_put; } else { @@ -621,8 +623,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, * hugepage split and collapse. */ local_irq_save(flags); - ptep = find_current_mm_pte(current->mm->pgd, - hva, NULL, NULL); + ptep = find_current_mm_pte(mm->pgd, hva, NULL, NULL); if (ptep) { pte = kvmppc_read_update_linux_pte(ptep, 1); if (__pte_write(pte))
Reduces the number of calls to get_current() in order to get the value of current->mm by doing it once and storing the value, since it is not supposed to change inside the same process). Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> --- Re-sending to all lists involved. (I missed kvm ones) arch/powerpc/kvm/book3s_64_mmu_hv.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)