On Mon, Mar 20, 2023 at 07:14:22PM +0800, haoxin wrote: > > 在 2023/3/20 上午4:32, Luis Chamberlain 写道: > > On Tue, Mar 14, 2023 at 10:46:28AM +0800, haoxin wrote: > > > All these series looks good to me and i do some test on my virtual machine > > > it works well. > > > > > > so please add Tested-by: Xin Hao<xhao@xxxxxxxxxxxxxxxxx> . > > > > > > just one question, if tmpfs pagecache occupies a large amount of memory, how > > > can we ensure successful memory reclamation in case of memory shortage? > > If you're disabling swap then you know the only thing you can do is > > unmount if you want to help the VM, otherwise the pressure is just > > greater for the VM. > > Un, what i mean is can we add a priority so that this type of pagecache is > reclaimed last ? That seems to be a classifier request for something much less aggressive than mapping_set_unevictable(). My patches *prior* to using mapping_set_unevictable() are I think closer to what it seems you want, but as noted before by folks, that also puts unecessary stress on the VM because just fail reclaim on our writepage(). > Instead of just setting the parameter noswap to make it unreclaimed, because > if such pagecache which occupy big part of memory which can not be > reclaimed, it will cause OOM. You can't simultaneously retain possession of a cake and eat it, too, once you eat it, its gone and noswap eats the cake because of the suggestion / decision to follow through with mapping_set_unevictable(). It sounds like you want to make mapping_set_unevictable() optional and deal with the possible stress incurred writepage() failing? Not quite sure what else to recommend here. Luis
