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From: Leo Martins <loemra.dev@gmail.com>
To: kernel test robot <oliver.sang@intel.com>, oe-lkp@lists.linux.dev
Cc: lkp@intel.com, linux-btrfs@vger.kernel.org, kernel-team@fb.com,
	David Sterba <dsterba@suse.com>
Subject: Re: [linux-next:master] [btrfs]  9a8eec6165:  fio.write_iops 22.6% regression
Date: Wed,  1 Jul 2026 16:44:11 -0700	[thread overview]
Message-ID: <20260701234412.4048647-1-loemra.dev@gmail.com> (raw)
In-Reply-To: <202603112240.f7605968-lkp@intel.com>

Hi Oliver,

Thanks for the report. I'm aware of this regression and the cause is
understood: the flagged commit adds a per-COW xarray store on every
COW'd metadata block, and on this single-task 4k randwrite ftruncate
workload that store is what costs the write_iops.

A fix has been posted to linux-btrfs that replaces the xarray with a
non-allocating fixed inline buffer and recovers the lost throughput:

  "btrfs: replace writeback inhibition xarray with a fixed inline buffer"

It carries the Reported-by and Closes tags pointing at this report.

Thanks,
Leo

  reply	other threads:[~2026-07-01 23:44 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-11 14:36 [linux-next:master] [btrfs] 9a8eec6165: fio.write_iops 22.6% regression kernel test robot
2026-07-01 23:44 ` Leo Martins [this message]
2026-07-02  1:55   ` Oliver Sang

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