erofs-snapshotter: make IMMUTABLE_FL optional to recover performance#12072
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fuweid merged 1 commit intocontainerd:mainfrom Jul 11, 2025
erofs:erofs-snapshotter
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erofs-snapshotter: make IMMUTABLE_FL optional to recover performance#12072fuweid merged 1 commit intocontainerd:mainfrom erofs:erofs-snapshotter
fuweid merged 1 commit intocontainerd:mainfrom
erofs:erofs-snapshotter
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AkihiroSuda
reviewed
Jul 9, 2025
AkihiroSuda
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Jul 9, 2025
AkihiroSuda
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Jul 9, 2025
cpuguy83
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Jul 9, 2025
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Hi @cpuguy83 @AkihiroSuda could you take a look again? Cc @dmcgowan @fuweid @djdongjin |
AkihiroSuda
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Jul 10, 2025
cpuguy83
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Jul 10, 2025
Enabling the IMMUTABLE_FL file attribute causes dirty data to be flushed synchronously at least on EXT4, which can greatly impact container launch performance. In contrast, the overlayfs snapshotter does not use syncfs by default. Most users may not need IMMUTABLE_FL, let's make IMMUTABLE_FL optional to align with the behavior of the overlayfs snapshotter and recover the original performance. 1. tensorflow Test commands: $ nerdctl image pull --snapshotter=X --unpack="false" tensorflow/tensorflow:2.19.0 $ time nerdctl container --snapshotter=X run -d tensorflow/tensorflow:2.19.0 /bin/sh Results: overlayfs | 0m18.748s erofs (no IMMUTABLE_FL) | 0m10.090s erofs (with IMMUTABLE_FL) | 0m21.074s 2. ubuntu 22.04 Test commands: $ nerdctl image pull --snapshotter=X --unpack="false" ubuntu:22.04 $ time nerdctl container --snapshotter=X run -d ubuntu:22.04 /bin/sh Results: overlayfs | 0m1.147s erofs (no IMMUTABLE_FL) | 0m0.795s erofs (with IMMUTABLE_FL) | 0m1.094s Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
cpuguy83
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Jul 10, 2025
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@AkihiroSuda need another try, it falls into flakyness sadly. :( |
fuweid
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Jul 11, 2025
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(... finally... I will try to cherry-pick it into 2.1 later since it impacts launch performance.) |
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Enabling the IMMUTABLE_FL file attribute causes dirty data to be flushed synchronously at least on EXT4[1], which can greatly impact container launch performance. In contrast, the overlayfs snapshotter does not use
syncfsby default.Most users may not need IMMUTABLE_FL, let's make IMMUTABLE_FL optional to align with the behavior of the overlayfs snapshotter and recover the original performance.
Test commands:
Results:
Test commands:
Results:
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/ext4/ioctl.c?h=v6.15#n636