Documentation fixup for stripe_cache_size
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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md.4
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@ -526,19 +526,22 @@ Finally, "idle" can be written to stop the check/repair process.
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.B md/stripe_cache_size
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.B md/stripe_cache_size
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This is only available on RAID5 and RAID6. It records the size (in
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This is only available on RAID5 and RAID6. It records the size (in
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pages per device) of the stripe cache which is used for synchronising
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pages per device) of the stripe cache which is used for synchronising
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all read and write operations to the array. The default is 128.
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all write operations to the array and all read operations if the array
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is degraded. The default is 256. Valid values are 17 to 32768.
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Increasing this number can increase performance in some situations, at
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Increasing this number can increase performance in some situations, at
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some cost in system memory.
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some cost in system memory. Note, setting this value too high can
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result in an "out of memory" condition for the system.
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memory_consumed = system_page_size * nr_disks * stripe_cache_size
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.TP
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.TP
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.B md/preread_bypass_threshold
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.B md/preread_bypass_threshold
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This is only available on RAID5 and RAID6. This variable sets the
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This is only available on RAID5 and RAID6. This variable sets the
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number of times MD will service a full-stripe-write before servicing a
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number of times MD will service a full-stripe-write before servicing a
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stripe that requires some "prereading". For fairness this defaults to
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stripe that requires some "prereading". For fairness this defaults to
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1. Setting this to 0 maximizes sequential-write throughput at the cost
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1. Valid values are 0 to stripe_cache_size. Setting this to 0
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of fairness to threads doing small or random writes. Valid values are 0
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maximizes sequential-write throughput at the cost of fairness to threads
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to stripe_cache_size.
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doing small or random writes.
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.SS KERNEL PARAMETERS
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.SS KERNEL PARAMETERS
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