Update ABD stats for linear page Linux #16729
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a10e552 updated abd_free_linear_page() to no longer call abd_update_scatter_stat(). This meant that linear pages that were not attached to Direct I/O requests were not doing waste accounting for the ARC. This led to performance issues due to incorrect ARC accounting that resulted in 100% of CPU time being spent in arc_evict() during prolonged I/O workloads with the ARC. The call to abd_update_scatter_stats() is now conditionally called in abd_free_linear_page() when the ABD is not from a Direct I/O request. Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
amotin
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behlendorf
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Nov 7, 2024
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Status: Accepted
tonynguien
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Nov 7, 2024
mmaybee
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Nov 7, 2024
behlendorf
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Nov 7, 2024
a10e552 updated abd_free_linear_page() to no longer call abd_update_scatter_stat(). This meant that linear pages that were not attached to Direct I/O requests were not doing waste accounting for the ARC. This led to performance issues due to incorrect ARC accounting that resulted in 100% of CPU time being spent in arc_evict() during prolonged I/O workloads with the ARC. The call to abd_update_scatter_stats() is now conditionally called in abd_free_linear_page() when the ABD is not from a Direct I/O request. Reviewed-by: Mark Maybee <mmaybee@delphix.com> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Signed-off-by: Brian Atkinson <batkinson@lanl.gov> Closes openzfs#16729
lundman
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Jan 26, 2025
a10e552 updated abd_free_linear_page() to no longer call abd_update_scatter_stat(). This meant that linear pages that were not attached to Direct I/O requests were not doing waste accounting for the ARC. This led to performance issues due to incorrect ARC accounting that resulted in 100% of CPU time being spent in arc_evict() during prolonged I/O workloads with the ARC. The call to abd_update_scatter_stats() is now conditionally called in abd_free_linear_page() when the ABD is not from a Direct I/O request. Reviewed-by: Mark Maybee <mmaybee@delphix.com> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Alexander Motin <mav@FreeBSD.org> Signed-off-by: Brian Atkinson <batkinson@lanl.gov> Closes openzfs#16729
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a10e552 updated abd_free_linear_page() to no longer call abd_update_scatter_stat(). This meant that linear pages that were not attached to Direct I/O requests were not doing waste accounting for the ARC. This led to performance issues due to incorrect ARC accounting that resulted in 100% of CPU time being spent in arc_evict() during prolonged I/O workloads with the ARC.
The call to abd_update_scatter_stats() is now conditionally called in abd_free_linear_page() when the ABD is not from a Direct I/O request.
Properly handling ARC waste accounting for linear page ABD's in Linux.
Motivation and Context
Without this change, ARC performance can degrade with 100% of the CPU time being spent in arc_evict() during prolonged I/O loads.
This issue was observed in #16728.
Description
Added abd_update_scatter_stat() back to abd_free_linear_page() so it is called in the event that the ABD is not from a Direct I/O request.
How Has This Been Tested?
Types of changes
Checklist:
Signed-off-by.