On Wed, Dec 28, 2016 at 04:30:25PM +0100, Michal Hocko wrote: > Hi, > while debugging [1] I've realized that there is some room for > improvements in the tracepoints set we offer currently. I had hard times > to make any conclusion from the existing ones. The resulting problem > turned out to be active list aging [2] and we are missing at least two > tracepoints to debug such a problem. > > Some existing tracepoints could export more information to see _why_ the > reclaim progress cannot be made not only _how much_ we could reclaim. > The later could be seen quite reasonably from the vmstat counters > already. It can be argued that we are showing too many implementation > details in those tracepoints but I consider them way too lowlevel > already to be usable by any kernel independent userspace. I would be > _really_ surprised if anything but debugging tools have used them. > > Any feedback is highly appreciated. > There is some minor overhead introduced in some paths regardless of whether the tracepoints are active or not but I suspect it's negligible in the context of the overhead of reclaim in general so; Acked-by: Mel Gorman <mgorman@xxxxxxx> -- Mel Gorman 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>