On Fri, Jul 28, 2023 at 01:33:47PM +0900, Sergey Senozhatsky wrote: > On (23/07/27 17:17), Tomasz Figa wrote: > > On Fri, Jun 30, 2023 at 7:47 PM Hsia-Jun Li wrote: > > > > > > Hello All > > > > > > This RFC tries to address the following problems: > > > > > > 1. Application may request too many buffers, increasing pressure to > > > system's memory allocator(Thinking about running Android with 8K UHD > > > playback in a system with only 2 GiB memory available); > > > > Yeah, I think that's something that has to be addressed. It was also > > mentioned recently in the review of the DELETE_BUF series. I think we > > need some kind of accounting of the allocations to the processes, so > > that the per-process limits of memory usage could apply. Let me add > > +Sergey Senozhatsky who often crosses his path with kernel memory > > management. > > That's an interesting topic. The usual approach would be memcg: we > create a memory controller, set memory usage limit, then move tasks > under that controller. The last part is problematic, as it implies > a well-behaving user-space. I'm not aware of a simple way (or any > way for that matter) to "automatically enforce" memcg on a process > group. > > From what I can tell networking code attempts to "enforce" memcg on its > allocations, and hence has to manually charge memcg. For instance, take > a look at sock_reserve_memory() and corresponding mem_cgroup_charge_skmem() > call. > > So I wonder if we can take a closer look at what networking does and > do something similar in vb2. It's a long-standing issue that would be nice to solve indeed. I however wonder if we should do so in vb2, or instead invest our time and efforts in transitioning to DMA heaps and solving the memory accounting issue there. -- Regards, Laurent Pinchart
