On Thu, 30 Oct 2014, Peter Zijlstra wrote: > On Wed, Oct 22, 2014 at 03:57:43PM +0200, Daniel Lezcano wrote: > > After discussing at the LPC2014 Dusseldorf, it appears the idea is > > good but the approach is wrong. The latency tracking must be done at > > the device level, per device and not in the task as what is doing this > > patchset. > > end_page_writeback()->test_clear_page_writeback()->__bdi_writeout_inc() > > Is the IO completion path that has a fair amount of statistics in, maybe > some of that is usable.
I had a look and I don't think it does what we need. The statistics in there are about estimating the device throughput for throttling writers. That doesn't help much for predicting when the next interrupt for the device is going to fire (some devices can do scatter-gather, some don't, etc.) And this doesn't cover the read path. Nicolas -- 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/
