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[76.182.20.124]) by smtp.gmail.com with ESMTPSA id oq7-20020a05620a610700b00767c961eb47sm4167614qkn.43.2023.08.01.06.57.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Aug 2023 06:57:48 -0700 (PDT) Date: Tue, 1 Aug 2023 09:57:47 -0400 From: Josef Bacik To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org, fstests@vger.kernel.org Subject: Re: [PATCH] btrfs/276: allow a slight increase in the number of extents Message-ID: <20230801135747.GA2012161@perftesting> References: <20230801065529.50122-1-wqu@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230801065529.50122-1-wqu@suse.com> Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Aug 01, 2023 at 02:55:29PM +0800, Qu Wenruo wrote: > [BUG] > Sometimes test case btrfs/276 would fail with extra number of extents: > > - output mismatch (see /opt/xfstests/results//btrfs/276.out.bad) > --- tests/btrfs/276.out 2023-07-19 07:24:07.000000000 +0000 > +++ /opt/xfstests/results//btrfs/276.out.bad 2023-07-28 04:15:06.223985372 +0000 > @@ -1,16 +1,16 @@ > QA output created by 276 > wrote 17179869184/17179869184 bytes at offset 0 > XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > -Number of non-shared extents in the whole file: 131072 > +Number of non-shared extents in the whole file: 131082 > Create a snapshot of 'SCRATCH_MNT' in 'SCRATCH_MNT/snap' > -Number of shared extents in the whole file: 131072 > ... > (Run 'diff -u /opt/xfstests/tests/btrfs/276.out /opt/xfstests/results//btrfs/276.out.bad' to see the entire diff) > > [CAUSE] > The test case uses golden output to record the number of total extents > of a 16G file. > > This is not reliable as we can have writeback happen halfway, resulting > smaller extents thus slightly more extents. > > With a VM with 4G memory, I have a chance around 1/10 hitting this > false alert. > > [FIX] > Instead of using golden output, we allow a slight (5%) float in the > number of extents, and move the 131072 (and 131072 - 16) from golden > output, so even if we have a slightly more extents, we can still pass > the test. > > Signed-off-by: Qu Wenruo Reviewed-by: Josef Bacik Thanks, Josef