On 27.10.2012 10:38, Thomas Gleixner wrote: > There is not much we can do about that unless we want to do a major > surgery on that pata driver code. > > So either you disable the throttler or you reconfigure the pata irq > thread to SCHED_OTHER, which will slow it down a bit, but avoids the > hogging of the machine with a RT task going wild. Thank you for the analysis. Yep I'll reconfigure it to SCHED_OTHER - file access is a totally low-prio thing in my application and I was more afraid of a possibility where someone fetching logfiles or something like that will bring the application to the knees. BTW what granularity does the throttler have? I cannot live with 50 ms lag once in a second, but in my case I can well live with 5 ms lag once in 100 ms (even if that means that the throttler would be activated more often). Right now I have CONFIG_TICK_ONESHOT=y CONFIG_NO_HZ=y CONFIG_HZ=1000 CONFIG_SCHED_HRTICK=y and lacking better choices my clock source is TSC. I admit that I do not know what precisely each setting does - the NO_HZ combined with HZ=1000 looks a bit weird ;) Best regards -- Stano -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html