I don't know exactly why the Linux kernel does this, but the pauses do not seem to occur for reads, so the Linux kernel is marking these pages read-only. A frie

I don't know exactly why the Linux kernel does this, but the pauses do not seem to occur for reads, so the Linux kernel is marking these pages read-only. A friend suggested this is the kernel's way of reducing the write I/O rate under overloaded conditions. If you know exactly why the kernel is doing this, I would love to hear it. What is happening is that the JVM is dirtying a previously clean page (this also happens in your test program, because the dirty pages in your mmap'ed file are being regularly written out - and therefore made clean - by background writeback). If, at this point, the global dirty limits are exceeded (/proc/sys/vm/dirty_bytes and /proc/sys/vm/dirty_ratio) then the task will be paused to throttle the generation of dirty pages.