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. -- tejun
