From a5ee6dfbf506424103d4de6579037836858bea72 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 18 Jul 2008 17:14:44 -0700 Subject: Document preread_bypass_threshold Signed-off-by: Dan Williams --- md.4 | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/md.4 b/md.4 index af1a7968..ef43d9d7 100644 --- a/md.4 +++ b/md.4 @@ -530,6 +530,15 @@ all read and write operations to the array. The default is 128. Increasing this number can increase performance in some situations, at some cost in system memory. +.TP +.B md/preread_bypass_threshold +This is only available on RAID5 and RAID6. This variable sets the +number of times MD will service a full-stripe-write before servicing a +stripe that requires some "prereading". For fairness this defaults to +1. Setting this to 0 maximizes sequential-write throughput at the cost +of fairness to threads doing small or random writes. Valid values are 0 +to stripe_cache_size. + .SS KERNEL PARAMETERS -- cgit v1.2.3