Hi Qu, On 02/05/2017 07:45 PM, Qu Wenruo wrote: > > > At 02/04/2017 09:47 AM, Jorg Bornschein wrote: >> February 4, 2017 1:07 AM, "Goldwyn Rodrigues" <rgoldwyn@xxxxxxx> wrote: <snipped> >> >> >> Quata support was indeed active -- and it warned me that the qroup >> data was inconsistent. >> >> Disabling quotas had an immediate impact on balance throughput -- it's >> *much* faster now! >> From a quick glance at iostat I would guess it's at least a factor 100 >> faster. >> >> >> Should quota support generally be disabled during balances? Or did I >> somehow push my fs into a weired state where it triggered a slow-path? >> >> >> >> Thanks! >> >> j > > Would you please provide the kernel version? > > v4.9 introduced a bad fix for qgroup balance, which doesn't completely > fix qgroup bytes leaking, but also hugely slow down the balance process: > > commit 62b99540a1d91e46422f0e04de50fc723812c421 > Author: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> > Date: Mon Aug 15 10:36:51 2016 +0800 > > btrfs: relocation: Fix leaking qgroups numbers on data extents > > Sorry for that. > > And in v4.10, a better method is applied to fix the byte leaking > problem, and should be a little faster than previous one. > > commit 824d8dff8846533c9f1f9b1eabb0c03959e989ca > Author: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> > Date: Tue Oct 18 09:31:29 2016 +0800 > > btrfs: qgroup: Fix qgroup data leaking by using subtree tracing > > > However, using balance with qgroup is still slower than balance without > qgroup, the root fix needs us to rework current backref iteration. > This patch has made the btrfs balance performance worse. The balance task has become more CPU intensive compared to earlier and takes longer to complete, besides hogging resources. While correctness is important, we need to figure out how this can be made more efficient. -- Goldwyn -- 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
