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From: Tomasz Chmielewski <tch@virtall.com>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [REGRESSION] Super slow balance in v5.0-rc1
Date: Mon, 14 Jan 2019 22:06:26 +0900	[thread overview]
Message-ID: <0b0e3f49ebec07edcb9ac4dafd3afa55@virtall.com> (raw)
In-Reply-To: <2c1782e8-b68a-4992-84e8-adeef34ca688@gmx.com>

On 2019-01-14 21:34, Qu Wenruo wrote:
> On 2019/1/14 下午7:47, Tomasz Chmielewski wrote:
>>> When rebasing my qgroup + balance optimization patches, I found one 
>>> very
>>> obvious performance regression for balance.
>>> 
>>> For normal 4G subvolume, 16 snapshots, balance workload, v4.20 kernel
>>> only takes 3s to relocate a metadata block group, while for v5.0-rc1, 
>>> I
>>> don't really know how it will take as it hasn't finished yet.
>> 
>> Are you sure it's v5.0-rc1 regression, not earlier?
> 
> At least for what I'm describing, yes. v5.0-rc1 introduced bug, and
> already pinned down.
> 
> So I'm afraid you're hitting another different bug.
> 
>> 
>> I'm trying to do a metadata-only balance from RAID-5 to RAID-1, with
>> 4.19.8.
>> 
>> It was going relatively "normal", until it got stuck and showing no
>> progress.
>> 
>> I've canceled the balance, upgraded to 4.20, started the balance 
>> again.> For straight 11 days, it rewrote terabytes of data on the 
>> disks, with no
>> progress at all.> Also, 4.19.8 had a balance interrupted because of 
>> "out
>> of space", despite we have terabytes free.
>> 
>> Metadata RAID-5 usage stays at 4.12GiB for the past 11 days (and a few
>> more days with 4.19.8).
> 
> Are you using qgroup? Which is another huge cause of slow balance.

No, no qgroups.

# btrfs quota rescan /data
ERROR: quota rescan failed: Invalid argument

  reply	other threads:[~2019-01-14 13:06 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-14 11:47 [REGRESSION] Super slow balance in v5.0-rc1 Tomasz Chmielewski
2019-01-14 12:34 ` Qu Wenruo
2019-01-14 13:06   ` Tomasz Chmielewski [this message]
  -- strict thread matches above, loose matches on Subject: below --
2019-01-14  5:39 Qu Wenruo
2019-01-14  9:35 ` David Sterba
2019-01-14 10:00   ` Qu Wenruo

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