Re: [UPDATED] A GUC variable to replace PGBE_ACTIVITY_SIZE - Mailing list pgsql-patches

From Heikki Linnakangas
Subject Re: [UPDATED] A GUC variable to replace PGBE_ACTIVITY_SIZE
Date
Msg-id 486A2143.4020604@enterprisedb.com
Whole thread Raw
In response to Re: [UPDATED] A GUC variable to replace PGBE_ACTIVITY_SIZE  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [UPDATED] A GUC variable to replace PGBE_ACTIVITY_SIZE  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-patches
Tom Lane wrote:
> "Heikki Linnakangas" <heikki@enterprisedb.com> writes:
>> Another simple optimization occurred to me while looking at this: we
>> should skip the memcpy/strcpy altogether if the BackendActivity slot is
>> not in use. That seems like a good bet, you usually don't try to max out
>> max_connections.
>
> Huh?  How could we be assigning to a slot that is not in use?

Before the patch, we loop through the shared PgBackendStatus slots
(there is MaxBackends of them), and issue a memcpy for each to copy it
to our local slot. After that, we check if it was actually in use.

After the patch, we still loop through the shared slots, but only issue
the memcpy for slots that are in use.

Hope this answers your question, I'm not sure what you meant...

--
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com

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