On 05.12.2017 02:02, Tejun Heo wrote: > Hello, Kirill. > > On Tue, Dec 05, 2017 at 01:49:42AM +0300, Kirill Tkhai wrote: >>> If the only reason is kernel memory consumption protection, the only >>> thing we need to do is making sure that memory used for aio commands >>> are accounted against cgroup kernel memory consumption and >>> relaxing/removing system wide limit. >> >> So, we just use GFP_KERNEL_ACCOUNT flag for allocation of internal aio >> structures and pages, and all the memory will be accounted in kmem and >> limited by memcg. Looks very good. > > Yeah. > >> One detail about memory consumption. io_submit() calls primitives >> file_operations::write_iter and read_iter. It's not clear for me whether >> they consume the same memory as if writev() or readv() system calls >> would be used instead. writev() may delay the actual write till dirty >> pages limit will be reached, so it seems logic of the accounting should >> be the same. So aio mustn't use more not accounted system memory in file >> system internals, then simple writev(). >> >> Could you please to say if you have thoughts about this? > > I'm not too familiar with vfs / filesystems but I don't think there's > gonna be significant unaccounted memory consumption. It shouldn't be > too difficult to find out with experiments too. > > Thanks. Thanks, Tejun! Kirill
