Re: [ADMIN] shared_buffers and shmmax - Mailing list pgsql-docs

Alvaro Herrera wrote:
> Bruce Momjian wrote:
>
> > I decided I didn't like what I did either;  updated version with new
> > headings and shorter descriptions:
> >
> >     http://momjian.us/tmp/pgsql/kernel-resources.html
>
> This version seems good to me, except please put back the B to the end
> of "770 k".

Patch applied with "B" re-added, though I would like to mention again
that it is inconsistent because we don't mention bytes in any other row
in that column.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +
Index: runtime.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v
retrieving revision 1.423
retrieving revision 1.424
diff -c -c -r1.423 -r1.424
*** runtime.sgml    16 Dec 2008 19:30:43 -0000    1.423
--- runtime.sgml    18 Dec 2008 17:03:09 -0000    1.424
***************
*** 1,4 ****
! <!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.423 2008/12/16 19:30:43 alvherre Exp $ -->

  <chapter Id="runtime">
   <title>Operating System Environment</title>
--- 1,4 ----
! <!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.424 2008/12/18 17:03:09 momjian Exp $ -->

  <chapter Id="runtime">
   <title>Operating System Environment</title>
***************
*** 1080,1120 ****


     <table id="shared-memory-parameters">
!     <title>Configuration parameters affecting
!     <productname>PostgreSQL</productname>'s shared memory usage</>

      <tgroup cols="2">
       <thead>
        <row>
!        <entry>Name</>
!        <entry>Approximate multiplier (bytes per increment) as of 8.3</>
        </row>
       </thead>

       <tbody>
        <row>
!        <entry><xref linkend="guc-max-connections"></>
!        <entry>1800 + 270 * <xref linkend="guc-max-locks-per-transaction"></entry>
        </row>

        <row>
!        <entry><xref linkend="guc-autovacuum-max-workers"></>
!        <entry>1800 + 270 * <xref linkend="guc-max-locks-per-transaction"></entry>
        </row>

        <row>
!        <entry><xref linkend="guc-max-prepared-transactions"></>
!        <entry>770 + 270 * <xref linkend="guc-max-locks-per-transaction"></entry>
        </row>

        <row>
!        <entry><xref linkend="guc-shared-buffers"></>
!        <entry>8400 (assuming 8 kB <symbol>BLCKSZ</>)</entry>
        </row>

        <row>
!        <entry><xref linkend="guc-wal-buffers"></>
!        <entry>8200 (assuming 8 kB <symbol>XLOG_BLCKSZ</>)</entry>
        </row>

        <row>
--- 1080,1124 ----


     <table id="shared-memory-parameters">
!     <title><productname>PostgreSQL</productname> shared memory usage</>

      <tgroup cols="2">
       <thead>
        <row>
!        <entry>Usage</>
!        <entry>Approximate shared memory bytes required (as of 8.3)</>
        </row>
       </thead>

       <tbody>
        <row>
!        <entry>Connections</>
!        <entry>(1800 + 270 * <xref
!        linkend="guc-max-locks-per-transaction">) * <xref
!        linkend="guc-max-connections"></entry>
        </row>

        <row>
!        <entry>Autovacuum workers</>
!        <entry>(1800 + 270 * <xref
!        linkend="guc-max-locks-per-transaction">) * <xref
!        linkend="guc-autovacuum-max-workers"></entry>
        </row>

        <row>
!        <entry>Prepared transactions</>
!        <entry>(770 + 270 * <xref
!        linkend="guc-max-locks-per-transaction">) * <xref linkend="guc-max-prepared-transactions"></entry>
        </row>

        <row>
!        <entry>Shared disk buffers</>
!        <entry>(<xref linkend="guc-block-size"> + 208) * <xref linkend="guc-shared-buffers"></entry>
        </row>

        <row>
!        <entry>WAL buffers</>
!        <entry>(<xref linkend="guc-wal-block-size"> + 8) * <xref linkend="guc-wal-buffers"></entry>
        </row>

        <row>
***************
*** 1125,1142 ****
      </tgroup>
     </table>

-    <note>
-     <para>
-      The multipliers for <varname>shared_buffers</> and
-      <varname>wal_buffers</> should be the number of buffers, not the
-      amount in bytes.  To find out the number of shared or wal buffers, divide
-      the amount in bytes by <xref linkend="guc-block-size"> and
-      <xref linkend="guc-wal-block-size">, respectively.
-     </para>
-    </note>
    </sect2>

-
    <sect2>
     <title>Resource Limits</title>

--- 1129,1136 ----