On 1/23/20 8:26 AM, Alexander Duyck wrote: >> The big piece I'm missing is the page cache. Linux will by default try >> to keep the free list as small as it can in favor of page cache, so most >> of the benefit of this patch set will be void in real world scenarios. > Agreed. This is a the next piece of this I plan to work on once this is > accepted. For now the quick and dirty approach is to essentially make use > of the /proc/sys/vm/drop_caches interface in the guest by either putting > it in a cronjob somewhere or to have it after memory intensive workloads. There was an implementation in "Clear Linux" that used this sysctl: > https://github.com/Conan-Kudo/omv-kernel-rc/blob/master/0154-sysctl-vm-Fine-grained-cache-shrinking.patch (I can't find it in the Clear repos at the moment, must not be used currently). But the idea was to have a little daemon in the host that periodically applied some artificial pressure with this sysctl. This sysctl is a smaller hammer than /proc/sys/vm/drop_caches and lets you drop small amounts of cache. The right way to do it is probably to do real, generic reclaim instead of drop_caches. This isn't conceptually *that* far away from the "proactive reclaim" that other folks have proposed: https://lwn.net/Articles/787611/
