On Thu 22-06-17 12:37:36, Andrew Morton wrote: [...] > > Me and a lot of other users have an issue where disk writes start fast (e.g. > > 200 MB/sec), but after intensive disk usage, they end up 100+ times slower > > (e.g. 2 MB/sec), and never get fast again until we run "echo 3 > > > /proc/sys/vm/drop_caches". What is your dirty limit configuration. Is your highmem dirtyable (highmem_is_dirtyable)? > > This issue happens on systems with any 4.x kernel, i386 arch, 16+ GB RAM. > > It doesn't happen if we use 3.x kernels (i.e. it's a regression) or any 64bit > > kernels (i.e. it only affects i386). I remember we've had some changes in the way how the dirty memory is throttled and 32b would be more sensitive to those changes. Anyway, I would _strongly_ discourage you from using 32b kernels with that much of memory. You are going to hit walls constantly and many of those issues will be inherent. Some of them less so but rather non-trivial to fix without regressing somewhere else. You can tune your system somehow but this will be fragile no mater what. Sorry to say that but 32b systems with tons of memory are far from priority of most mm people. Just use 64b kernel. There are more pressing problems to deal with. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
