Hi! On Wed 28-12-16 14:09:51, Michal Hocko wrote: > I would like to propose the following for LSF/MM discussion. Both MM and > FS people should be involved. > > The current way of the slab reclaim is rather suboptimal from 2 > perspectives. > > 1) The slab allocator relies on shrinkers to release pages but shrinkers > are object rather than page based. This means that the memory reclaim > asks to free some pages, slab asks shrinkers to free some objects > and the result might be that nothing really gets freed even though > shrinkers do their jobs properly because some objects are still pinning > the page. This is not a new problem and it has been discussed in the > past. Dave Chinner has even suggested a solution [1] which sounds like > the right approach. There was no follow up and I believe we should > into implementing it. > > 2) The way we scale slab reclaim pressure depends on the regular LRU > reclaim. There are workloads which do not general a lot of pages on LRUs > while they still consume a lot of slab memory. We can end up even going > OOM because the slab reclaim doesn't free up enough. I am not really > sure how the proper solution should look like but either we need some > way of slab consumption throttling or we need a more clever slab > pressure estimation. > > [1] https://lkml.org/lkml/2010/2/8/329. I'm interested in this topic although I think it currently needs more coding and experimenting than discussions... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
