ZIL: Reduce maximum size of WR_COPIED to 7.5KB #15353
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Benchmarks show that at certain write sizes range lock/unlock take not so much time as extra memory copy. The exact threshold is not obvious due to other overheads, but it is definitely lower than ~63KB used before. Make it configurable, defaulting at 7.5KB, that is 8KB of nearest malloc() size minus itx and lr structs. Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored by: iXsystems, Inc.
behlendorf
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Benchmarks show that at certain write sizes range lock/unlock take not so much time as extra memory copy. The exact threshold is not obvious due to other overheads, but it is definitely lower than ~63KB used before. Make it configurable, defaulting at 7.5KB, that is 8KB of nearest malloc() size minus itx and lr structs. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored by: iXsystems, Inc. Closes openzfs#15353
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Benchmarks show that at certain write sizes range lock/unlock take not so much time as extra memory copy. The exact threshold is not obvious due to other overheads, but it is definitely lower than ~63KB used before. Make it configurable, defaulting at 7.5KB, that is 8KB of nearest malloc() size minus itx and lr structs. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored by: iXsystems, Inc. Closes #15353
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Benchmarks show that at certain write sizes range lock/unlock take not so much time as extra memory copy. The exact threshold is not obvious due to other overheads, but it is definitely lower than ~63KB used before. Make it configurable, defaulting at 7.5KB, that is 8KB of nearest malloc() size minus itx and lr structs. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored by: iXsystems, Inc. Closes openzfs#15353
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Benchmarks show that at certain write sizes range lock/unlock take not so much time as extra memory copy. The exact threshold is not obvious due to other overheads, but it is definitely lower than ~63KB used before. Make it configurable, defaulting at 7.5KB, that is 8KB of nearest malloc() size minus itx and lr structs.
Previously some bigger size could be beneficial due to WR_NEED_COPY getting the data under the zl_issue_lock, increasing its contention, but it is no longer a thing after #15122.
This is a part of #14909.
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