2011/12/1 Alexandre Oliva <oliva@xxxxxxxxxxxxxxxxx>: > On Nov 29, 2011, Christian Brunner <chb@xxxxxx> wrote: > >> When I'm doing havy reading in our ceph cluster. The load and wait-io >> on the patched servers is higher than on the unpatched ones. > > That's unexpected. > >> This seems to be coming from "btrfs-endio-1". A kernel thread that has >> not caught my attention on unpatched systems, yet. > > I suppose I could wave my hands while explaining that you're getting > higher data throughput, so it's natural that it would take up more > resources, but that explanation doesn't satisfy me. I suppose > allocation might have got slightly more CPU intensive in some cases, as > we now use bitmaps where before we'd only use the cheaper-to-allocate > extents. But that's unsafisfying as well. I must admit, that I do not completely understand the difference between bitmaps and extents. >From what I see on my servers, I can tell, that the degradation over time is gone. (Rebooting the servers every day is no longer needed. This is a real plus.) But the performance compared to a freshly booted, unpatched server is much slower with my ceph workload. I wonder if it would make sense to initialize the list field only, when the cluster setup fails? This would avoid the fallback to the much unclustered allocation and would give us the cheaper-to-allocate extents. Regards, Christian -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
