On Tue, Sep 23, 2008 at 10:48 AM, KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote: > Why vm_dirty_ratio = 0.125 is wrong? > it is hardly for parser maker, but it have nicer user experience. Here's an idea to build off Kosaki's suggestion and incorporate other previous suggestions. What if we have two knobs for every ratio. So we could have vm_dirty_ratio and also vm_dirty_KB vm_dirty_KB allows the user to set the number of KB desired and also read the amount of KB that has been set. Writing to vm_dirty_ratio works just as before and only allows whole percentages. Reading from vm_dirty_ratio will return a reply as before except if KB has been set it can return a number in percentages (rounded off to thousandths). This way we allow new functionality and preserve old functionality while not surprising the user. Maybe we should deprecate the vm_dirty_ratio interface also and point folks to the vm_dirty_KB. > We don't have any motivation of its interface change. We are seeing problems where we are generating a lot of dirty memory from asynchronous background writes while more important traffic is operating with DIRECT_IO. The DIRECT_IO traffic will incur high latency spikes as the pdflush hits the background threshold and tries to write a lot of dirty buffers at once. What we want to do is lower the background threshold low enough so that we don't end up writing a lot of data at one time. As systems get more and more memory this is and will become difficult. 1% of system RAM could tie up a disk. mrubin _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers