On 05/09/2014 08:12 AM, Jens Axboe wrote: > On 05/09/2014 03:17 AM, Matias Bjørling wrote: >> With multi-million IOPS and multi-node workloads, the atomic_t in_flight >> tracking becomes a bottleneck. Change the in-flight accounting to per-cpu >> counters to elevate. > > The part stats are a pain in the butt, I've tried to come up with a > great fix for them too. But I don't think the percpu conversion is > necessarily the right one. The summing is part of the hotpath, so percpu > counters aren't necessarily the right way to go. I don't have a better > answer right now, otherwise it would have been fixed :-)
Actual data point - this slows my test down ~14% compared to the stock kernel. Also, if you experiment with this, you need to watch for the out-of-core users of the part stats (like DM). -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
