On Mon, May 01, 2023 at 09:54:10AM -0700, Suren Baghdasaryan wrote: > Performance overhead: > To evaluate performance we implemented an in-kernel test executing > multiple get_free_page/free_page and kmalloc/kfree calls with allocation > sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU > affinity set to a specific CPU to minimize the noise. Below is performance > comparison between the baseline kernel, profiling when enabled, profiling > when disabled (nomem_profiling=y) and (for comparison purposes) baseline > with CONFIG_MEMCG_KMEM enabled and allocations using __GFP_ACCOUNT: > > kmalloc pgalloc > Baseline (6.3-rc7) 9.200s 31.050s > profiling disabled 9.800 (+6.52%) 32.600 (+4.99%) > profiling enabled 12.500 (+35.87%) 39.010 (+25.60%) > memcg_kmem enabled 41.400 (+350.00%) 70.600 (+127.38%) Hm, this makes me think we have a regression with memcg_kmem in one of the recent releases. When I measured it a couple of years ago, the overhead was definitely within 100%. Do you understand what makes the your profiling drastically faster than kmem? Thanks!
