Johannes Weiner <han...@cmpxchg.org> writes: > On Thu, Apr 20, 2017 at 08:50:43AM +0800, Huang, Ying wrote: >> Johannes Weiner <han...@cmpxchg.org> writes: >> > On Wed, Apr 19, 2017 at 03:06:24PM +0800, Huang, Ying wrote: >> >> With the patchset, the swap out throughput improves 3.6% (from about >> >> 4.16GB/s to about 4.31GB/s) in the vm-scalability swap-w-seq test case >> >> with 8 processes. The test is done on a Xeon E5 v3 system. The swap >> >> device used is a RAM simulated PMEM (persistent memory) device. To >> >> test the sequential swapping out, the test case creates 8 processes, >> >> which sequentially allocate and write to the anonymous pages until the >> >> RAM and part of the swap device is used up. >> >> >> >> Cc: Johannes Weiner <han...@cmpxchg.org> >> >> Signed-off-by: "Huang, Ying" <ying.hu...@intel.com> >> >> Acked-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com> [for >> >> can_split_huge_page()] >> > >> > How often does this actually happen in practice? Because all that this >> > protects us from is trying to allocate a swap cluster - which with the >> > si->free_clusters list really isn't all that expensive - and return it >> > again. Unless this happens all the time in practice, this optimization >> > seems misplaced. >> >> To my surprise too, I found this patch has measurable impact in my >> test. The swap out throughput improves 3.6% in the vm-scalability >> swap-w-seq test case with 8 processes. Details are in the original >> patch description. > > Yeah I think that justifies it. > > The changelog says "the patchset", I didn't realize this is the gain > from just this patch alone. Care to update that?
Sorry for confusing, will update it in the next version. Best Regards, Huang, Ying > Thanks!
