On Fri, May 13, 2022 at 06:51:30PM +0300, Vasily Averin wrote: > Below is tracing results of mkdir /sys/fs/cgroup/vvs.test on > 4cpu VM with Fedora and self-complied upstream kernel. The calculations > are not precise, it depends on kernel config options, number of cpus, > enabled controllers, ignores possible page allocations etc. > However this is enough to clarify the general situation: > - Total sum of accounted memory is ~60Kb. > - Accounted only 2 huge percpu allocation marked '=', ~18Kb. > (and can be 0 without memory controller) > - kernfs nodes and iattrs are among the main memory consumers. > they are marked '+' to be accounted. > - cgroup_mkdir always allocates 4Kb, > so I think it should be accounted first too. > - mem_cgroup_css_alloc allocations consumes 10K, > it's enough to be accounted, especially for VMs with 1-2 CPUs > - Almost all other allocations are quite small and can be ignored. > Exceptions are percpu allocations in alloc_fair_sched_group(), > this can consume a significant amount of memory on nodes > with multiple processors. > - kernfs nodes consumes ~6Kb memory inside simple_xattr_set() > and simple_xattr_alloc(). This is quite high numbers, > but is not critical, and I think we can ignore it at the moment. > - If all proposed memory will be accounted it gives us ~47Kb, > or ~75% of all allocated memory. > > number bytes $1*$2 sum note call_site > of alloc > allocs > ------------------------------------------------------------ > 1 14448 14448 14448 = percpu_alloc_percpu: > 1 8192 8192 22640 + (mem_cgroup_css_alloc+0x54) > 49 128 6272 28912 + (__kernfs_new_node+0x4e) > 49 96 4704 33616 ? (simple_xattr_alloc+0x2c) > 49 88 4312 37928 + (__kernfs_iattrs+0x56) > 1 4096 4096 42024 + (cgroup_mkdir+0xc7) > 1 3840 3840 45864 = percpu_alloc_percpu: > 4 512 2048 47912 + (alloc_fair_sched_group+0x166) > 4 512 2048 49960 + (alloc_fair_sched_group+0x139) > 1 2048 2048 52008 + (mem_cgroup_css_alloc+0x109) > 49 32 1568 53576 ? (simple_xattr_set+0x5b) > 2 584 1168 54744 (radix_tree_node_alloc.constprop.0+0x8d) > 1 1024 1024 55768 (cpuset_css_alloc+0x30) > 1 1024 1024 56792 (alloc_shrinker_info+0x79) > 1 768 768 57560 percpu_alloc_percpu: > 1 640 640 58200 (sched_create_group+0x1c) > 33 16 528 58728 (__kernfs_new_node+0x31) > 1 512 512 59240 (pids_css_alloc+0x1b) > 1 512 512 59752 (blkcg_css_alloc+0x39) > 9 48 432 60184 percpu_alloc_percpu: > 13 32 416 60600 (__kernfs_new_node+0x31) > 1 384 384 60984 percpu_alloc_percpu: > 1 256 256 61240 (perf_cgroup_css_alloc+0x1c) > 1 192 192 61432 percpu_alloc_percpu: > 1 64 64 61496 (mem_cgroup_css_alloc+0x363) > 1 32 32 61528 (ioprio_alloc_cpd+0x39) > 1 32 32 61560 (ioc_cpd_alloc+0x39) > 1 32 32 61592 (blkcg_css_alloc+0x6b) > 1 32 32 61624 (alloc_fair_sched_group+0x52) > 1 32 32 61656 (alloc_fair_sched_group+0x2e) > 3 8 24 61680 (__kernfs_new_node+0x31) > 3 8 24 61704 (alloc_cpumask_var_node+0x1b) > 1 24 24 61728 percpu_alloc_percpu: > > This patch-set enables accounting for required resources. > I would like to discuss the patches with cgroup developers and maintainers, > then I'm going re-send approved patches to subsystem maintainers. Hi Vasily! Thank you for the analysis and for the series. It looks really good to me. Please, feel free to add Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx> for the whole series. Thanks!
