| Message ID | 20190822075151.24838-4-atish.patra@wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Optimize tlbflush path | expand |
On Thu, Aug 22, 2019 at 12:51:51AM -0700, Atish Patra wrote: > If tlbflush request is for page only, there is no need to do a > complete local tlb shootdown. > > Just do a local tlb flush for the given address. Looks good, although I suspect in many cases even doing multiple single-page sfence.vma calls might be cheaper than the global one. But I think that is worth a Ń•eparate discussion, preferably with actual numbers. Reviewed-by: Christoph Hellwig <hch@lst.de>
On Thu, 2019-08-22 at 10:11 +0200, Christoph Hellwig wrote: > On Thu, Aug 22, 2019 at 12:51:51AM -0700, Atish Patra wrote: > > If tlbflush request is for page only, there is no need to do a > > complete local tlb shootdown. > > > > Just do a local tlb flush for the given address. > > Looks good, although I suspect in many cases even doing multiple > single-page sfence.vma calls might be cheaper than the global one. > > But I think that is worth a Ń•eparate discussion, preferably with > actual > numbers. > Yup. Finding a good threashold is always tricky without real benchmarks. > Reviewed-by: Christoph Hellwig <hch@lst.de> Thanks for the review.
diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c index 8172fbf46123..b1c04751bcf1 100644 --- a/arch/riscv/mm/tlbflush.c +++ b/arch/riscv/mm/tlbflush.c @@ -27,7 +27,10 @@ static void __sbi_tlb_flush_range(struct cpumask *cmask, unsigned long start, if (cpumask_any_but(cmask, cpuid) >= nr_cpu_ids) { /* local cpu is the only cpu present in cpumask */ - local_flush_tlb_all(); + if (size <= PAGE_SIZE) + local_flush_tlb_page(start); + else + local_flush_tlb_all(); } else { riscv_cpuid_to_hartid_mask(cmask, &hmask); sbi_remote_sfence_vma(cpumask_bits(&hmask), start, size);
If tlbflush request is for page only, there is no need to do a complete local tlb shootdown. Just do a local tlb flush for the given address. Signed-off-by: Atish Patra <atish.patra@wdc.com> --- arch/riscv/mm/tlbflush.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)