On Tue, Jan 26, 2016 at 12:26 PM, Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > On Tue, Jan 26, 2016 at 1:54 AM, Christian Rohmann > <crohmann@xxxxxxxxxxxxx> wrote: >> Hey Chris and all, >> >> On 01/25/2016 11:13 PM, Chris Murphy wrote: >>> Does anyone suspect a kernel regression here? I wonder if its worth it >>> to suggest testing the current version of all fairly recent kernels: >>> 4.5.rc1, 4.4, 4.3.4, 4.2.8, 4.1.16? I think going farther back to >>> 3.18.x isn't worth it since that's before the major work since raid56 >>> was added. Quite a while ago I've done a raid56 rebuild and balance >>> that was pretty fast but it was only a 4 or 5 device test. >> >> Problem is that this balance did not work before going to 4.4 kernel, >> it's was simply crashing after about an hour or two of runtime. >> >> Currently I am using 4.4 kernel + btrfs-progs, so apart from 4.5rc1 I >> can not get any more bleeding edge. >> >> 4.5 I am happy to try, but not RC1 as there are already some bugs >> popping up regarding the BTRFS changes. >> >> >> On 01/26/2016 07:14 AM, Chris Murphy wrote: >>> Christian, what are you getting for 'iotop -d3 -o' or 'iostat -d3'. Is >>> it consistent or is it fluctuating all over the place? What sort of >>> eyeball avg/min/max are you getting? >> >> "1672.81 K/s 1672.81 K/s 0.00 % 6.99 % btrfs balance start -dstripes >> 1..11 -mstripes 1..11 " >> >> but it's jumping up to 25MB/s for a few polls, but most of the time it's >> at 1.3 to 1.7 MB/s > > > That is really slow. The fact you can't balance without crashing prior > to a 4.4 kernel makes me suspicious about the file system state. What > about reading and writing files? What's the performance in that case? > Is it just the balance that's this slow? Do you have the call traces > for older kernel crashes with balance? What btrfs-progs was used to > create the raid6 volume? > > Maybe the slowness is due to the -dstripes -mstripes filter. That's > relatively new. And I didn't try that. And I also don't really > understand the values you picked either. Seems to me if you've added > four drives relatively recently, there won't be many chunks using > 12-strip stripes, most of them will be 8-strip stripes. So I don't > really know what you're limiting. I guess the bottom line of what I'm suggesting before trying anything else, is to stop the balance and start a normal one without filters and see how that performs. -- Chris Murphy -- 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
