Hi, Michal, Michal Hocko <mhocko@xxxxxxxxxx> writes: > On Fri 18-05-18 11:03:16, Huang, Ying wrote: > [...] >> The patch is a generic optimization which should benefit quite some >> workloads, not for a specific use case. To demonstrate the performance >> benefit of the patch, we tested it with vm-scalability run on >> transparent huge page. > > It is also adds quite some non-intuitive code. So is this worth? Does > any _real_ workload benefits from the change? I don't have any _real_ workload which benefits from this. But I think this is the right way to copy the huge page. It should benefit many workloads with heavy cache contention, as illustrated in the micro-benchmark. But the performance benefit may be small or non-measurable for the _real_ workload. The code does become not as intuitive as before. But fortunately, all non-intuitive code are in copy_user_huge_page(), which is a leaf function with well defined interface and semantics. And with the help of the code comments, at least the intention of the code is clear. Best Regards, Huang, Ying >> include/linux/mm.h | 3 ++- >> mm/huge_memory.c | 3 ++- >> mm/memory.c | 43 +++++++++++++++++++++++++++++++++++++++---- >> 3 files changed, 43 insertions(+), 6 deletions(-)
