On Wed, 24 Oct 2012 08:29:45 +0200 Michal Hocko <mhocko@xxxxxxx> wrote: > > > > > > + printk(KERN_NOTICE "%s (%d): dropped kernel caches: %d\n", > > > + current->comm, task_pid_nr(current), sysctl_drop_caches); > > > > urgh. Are we really sure we want to do this? The system operators who > > are actually using this thing will hate us :( > > I have no problems with lowering the priority (how do you see > KERN_INFO?) but shouldn't this message kick them that they are doing > something wrong? Or if somebody uses that for "benchmarking" to have a > clean table before start is this really that invasive? hmpf. This patch worries me. If there are people out there who are regularly using drop_caches because the VM sucks, it seems pretty obnoxious of us to go dumping stuff into their syslog. What are they supposed to do? Stop using drop_caches? But that would unfix the problem which they fixed with drop_caches in the first case. And they might not even have control over the code - they need to go back to their supplier and say "please send me a new version", along with all the additional costs and risks involed in an update. > > More friendly alternatives might be: > > > > - Taint the kernel. But that will only become apparent with an oops > > trace or similar. > > > > - Add a drop_caches counter and make that available in /proc/vmstat, > > show_mem() output and perhaps other places. > > We would loose timing and originating process name in both cases which > can be really helpful while debugging. It is fair to say that we could > deduce the timing if we are collecting /proc/meminfo or /proc/vmstat > already and we do collect them often but this is not the case all of the > time and sometimes it is important to know _who_ is doing all this. But how important is all that? The main piece of information the kernel developer wants is "this guy is using drop_caches a lot". All the other info is peripheral and can be gathered by other means if so desired. -- 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>