On Fri 07-08-15 18:16:47, PINTU KUMAR wrote: [...] > > On Fri 07-08-15 12:38:54, Pintu Kumar wrote: > > > This patch add new counter slowpath_entered in /proc/vmstat to track > > > how many times the system entered into slowpath after first allocation > > > attempt is failed. > > > > This is too lowlevel to be exported in the regular user visible interface > > IMO. > > > I think its ok because I think this interface is for lowlevel debugging > itself.
Yes but this might change in future implementations where the counter might be misleading or even lacking any meaning. This is a user visible interface which has to be maintained practically for ever. We have made those mistakes in the past... [...] > This information is good for kernel developers. Then make it a trace point and you can dump even more information. E.g. timestamps, gfp_mask, order... [...] > Regarding trace points, I am not sure if we can attach counter to it. You do not need to have a counter. You just watch for the tracepoint while debugging your particular problem. > Also trace may have more over-head Tracepoints should be close to 0 overhead when disabled and certainly not a performance killer during the debugging session. > and requires additional configs to be enabled to debug. This is to be expected for the debugging sessions. And I am pretty sure that the static event tracepoints do not require anything really excessive. > Mostly these configs will not be enabled by default (at least in embedded, low > memory device). Are you sure? I thought that CONFIG_TRACING should be sufficient for EVENT_TRACING but I am not familiar with this too deeply... -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
