On Mon, 24 Oct 2011, Satoru Moriya wrote: > >> We do. > >> Basically we need this kind of feature for almost all our latency > >> sensitive applications to avoid latency issue in memory allocation. > >> > > > > These are all realtime? > > Do you mean that these are all realtime process? > > If so, answer is depending on the situation. In the some situations, > we can set these applications as rt-task. But the other situation, > e.g. using some middlewares, package softwares etc, we can't set them > as rt-task because they are not built for running as rt-task. And also > it is difficult to rebuilt them for working as rt-task because they > usually have huge code base. > If this problem affects processes that aren't realtime, then your only option is to increase /proc/sys/vm/min_free_kbytes. It's unreasonable to believe that the VM should be able to reclaim in the background at the same rate that an application is allocating huge amounts of memory without allowing there to be a buffer. Adding another tunable isn't going to address that situation better than min_free_kbytes. > As I reported another mail, changing kswapd priority does not mitigate > even my simple testcase very much. Of course, reclaiming above the high > wmark may solve the issue on some workloads but if an application can > allocate memory more than high wmark - min wmark which is extended and > fast enough, latency issue will happen. > Unless this latency concern is fixed, customers doesn't use vanilla > kernel. > And you have yet to provide an expression that shows what a sane setting for this tunable will be. In fact, it seems like you're just doing trial and error and finding where it works pretty well for a certain VM implementation in a certain kernel. That's simply not a maintainable userspace interface! -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>