Change fsync(2) optimization to per-file #1159
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The zfs_fsyncer_key TSD was added as a performance optimization to reduce contention on the zl_lock from zil_commit(). This issue manifested itself as very long (100+ms) system call times for fsync(2) heavy workloads. However, we'd like to eliminate the usage of TSD in ZoL while keeping this optimization. There is no native Linux kernel equivilant of TSD and the SPLs implementation is primitive. It would simply be best to remove all the TSD consumers. To achieve this the zfs_fsyncer_key TSD counter has been reworked to be per-file instead of per-thread. This is not expected to behave significantly differently than the original implementation for real workloads. This just leaves one small ZFS TSD consumer. If it can be cleanly removed from the code we'll be able to shed the SPL TSD implementation entirely. Signed-off-by: Brian Behlendorf <[email protected]> Issue openzfs/spl#174
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Closing, this won't be merged. The core issue in the TSD implementation was resolved instead. Although I'd still love to kill off all the tsd consumers, but that can wait for another day. |
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The zfs_fsyncer_key TSD was added as a performance optimization
to reduce contention on the zl_lock from zil_commit(). This
issue manifested itself as very long (100+ms) system call
times for fsync(2) heavy workloads.
However, we'd like to eliminate the usage of TSD in ZoL while
keeping this optimization. There is no native Linux kernel
equivilant of TSD and the SPLs implementation is primitive.
It would simply be best to remove all the TSD consumers.
To achieve this the zfs_fsyncer_key TSD counter has been
reworked to be per-file instead of per-thread. This is not
expected to behave significantly differently than the original
implementation for real workloads.
This just leaves one small ZFS TSD consumer. If it can be
cleanly removed from the code we'll be able to shed the SPL
TSD implementation entirely.
Signed-off-by: Brian Behlendorf [email protected]
Issue openzfs/spl#174