SCHDOPT1 parameter: Difference between revisions
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Flags that, in addition to the [[SCHDOPT parameter]], allows one to tune scheduler behavior. <var>SCHDOPT1</var> is a parameter where the following bits control a certain aspects of scheduler behavior: | |||
<table> | <table> | ||
<tr class="head"><th>Setting</th><th>Meaning</th></tr> | <tr class="head"><th>Setting</th><th>Meaning</th></tr> | ||
<tr><th align="right"><var>X'01'</var></th> | <tr><th align="right"><var>X'01'</var></th> | ||
<td> | <td>Indicates that threads that are running on a zIIP-capable SRB and need to do journal I/O do not "bounce" to a non-zIIP subtask to do the journal or checkpoint I/O but simply perform it on the maintask. Since generally very little processing is involved in doing journal or checkpoint I/O, sending a thread to an MP task to do the I/O only increases latency and saves no maintask processing overhead. | ||
This setting also prevents a thread running on a non-zIIP task and that has to wait for another thread doing journal or checkpoint I/O before doing the same from bouncing between maintask and subtask to do the I/O – when the X'01' bit is set, the I/O will be performed on the maintask, again reducing I/O latency. This bit has a much more significant effect if zIIP subtasks are in use. For more information about zIIP processing, refer to the [[SCHDOPT parameter]] and [[AMPSUBZ parameter]] descriptions. | |||
</td></tr> | |||
</table> | </table> | ||
Revision as of 13:35, 21 June 2020
Flags that, in addition to the SCHDOPT parameter, allows one to tune scheduler behavior. SCHDOPT1 is a parameter where the following bits control a certain aspects of scheduler behavior:
| Setting | Meaning |
|---|---|
| X'01' | Indicates that threads that are running on a zIIP-capable SRB and need to do journal I/O do not "bounce" to a non-zIIP subtask to do the journal or checkpoint I/O but simply perform it on the maintask. Since generally very little processing is involved in doing journal or checkpoint I/O, sending a thread to an MP task to do the I/O only increases latency and saves no maintask processing overhead.
This setting also prevents a thread running on a non-zIIP task and that has to wait for another thread doing journal or checkpoint I/O before doing the same from bouncing between maintask and subtask to do the I/O – when the X'01' bit is set, the I/O will be performed on the maintask, again reducing I/O latency. This bit has a much more significant effect if zIIP subtasks are in use. For more information about zIIP processing, refer to the SCHDOPT parameter and AMPSUBZ parameter descriptions. |