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| author | Ronnie Sahlberg <ronniesahlberg@gmail.com> | 2012-03-20 11:38:20 +1100 |
|---|---|---|
| committer | Ronnie Sahlberg <ronniesahlberg@gmail.com> | 2012-03-20 11:39:11 +1100 |
| commit | 9bc6055af8e881635ceec9cbe5df51677cf945bc (patch) | |
| tree | 80598b3bab16bec956becc2d067da8970263c76d | |
| parent | c051f67d674beb52419c4c30b163db397e7861b2 (diff) | |
| download | samba-9bc6055af8e881635ceec9cbe5df51677cf945bc.tar.gz samba-9bc6055af8e881635ceec9cbe5df51677cf945bc.tar.xz samba-9bc6055af8e881635ceec9cbe5df51677cf945bc.zip | |
DOC document the FetchCollapse tunable
(This used to be ctdb commit c37aa6f3738693653f64c2fa015ace061da38b5a)
| -rw-r--r-- | ctdb/doc/ctdbd.1.xml | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/ctdb/doc/ctdbd.1.xml b/ctdb/doc/ctdbd.1.xml index 589a8247f0..2dc723d55a 100644 --- a/ctdb/doc/ctdbd.1.xml +++ b/ctdb/doc/ctdbd.1.xml @@ -963,6 +963,29 @@ </para> </refsect2> + <refsect2><title>FetchCollapse</title> + <para>Default: 1</para> + <para> + When many clients across many nodes try to access the same record at the + same time this can lead to a fetch storm where the record becomes very + active and bounces between nodes very fast. This leads to high CPU + utilization of the ctdbd daemon, trying to bounce that record around + very fast, and poor performance. + </para> + <para> + This parameter is used to activate a fetch-collapse. A fetch-collapse + is when we track which records we have requests in flight so that we only + keep one request in flight from a certain node, even if multiple smbd + processes are attemtping to fetch the record at the same time. This + can improve performance and reduce CPU utilization for certain + workloads. + </para> + <para> + This timeout controls if we should collapse multiple fetch operations + of the same record into a single request and defer all duplicates or not. + </para> + </refsect2> + </refsect1> <refsect1><title>LVS</title> |