Thanks for looking at this. On Sat, Jun 19, 2010 at 1:17 AM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote: > Michael Rubin <mrubin@xxxxxxxxxx> writes: >> # cat /sys/block/sda/bdi/writeback_stats >> balance dirty pages 0 >> balance dirty pages waiting 0 >> periodic writeback 92024 >> periodic writeback exited 0 >> laptop periodic 0 >> laptop or bg threshold 0 >> free more memory 0 >> try to free pages 271 >> syc_sync 6 >> sync filesystem 0 > > That exports a lot of kernel internals in /sys, presumably read by some > applications. What happens with the applications if the kernel internals > ever change? Will the application break? > > It would be bad to not be able to change the kernel because of > such an interface. I agree. This would put the kernel in a box a bit. Some of them (sys_sync, periodic writeback, free_more_memory) I feel are generic enough concepts that with some rewording of the labels they could be exposed with no issue. "Balance_dirty_pages" is an example where that won't work. Are there alternatives to this? Maybe tracepoints that are compiled to be on? A CONFIG_WRITEBACK_DEBUG that would expose this file? Having this set of info readily available and collected makes debugging a lot easier. But I admit I am not sure the best way to expose them. mrubin -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
