On Wed 27-11-19 15:40:19, Cristopher Lameter wrote: > On Tue, 26 Nov 2019, Michal Hocko wrote: > > > > I have no idea about what this is. > > > > It seems to be there since the initial merge. I suspect this is just > > following a generic sysfs rule that each file has to provide those > > events? > > I have never heard of anyone using this. > > > > There have been many people who > > > reworked the sysfs support and this has been the cause for a lot of > > > breakage over the years. > > > > Remember any specifics? > > The sequencing of setup / teardown of sysfs entries has frequently been > a problem and that caused numerous issues with slab initialization as well > as kmem cache creation. Initially kmalloc DMA caches were created on > demand which caused some issues. Then there was the back and forth with > cache aliasing during kmem_cache_create() that caused another set of > instabilities. > > > I am mostly interested in potential users. In other words I am thinking > > to suppress those events. There is already ke knob to control existence > > of memcg caches but I do not see anything like this for root caches. > > > > I am not aware of any users but the deployments of Linux are so diverse > these days that I am not sure that there are no users. Would you mind a patch that would add a kernel command line parameter that would work like memcg_sysfs_enabled? The default for the config would be on. Or it would be preferrable to simply drop only events? -- Michal Hocko SUSE Labs
