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PERFORMANCE IMPROVEMENT by mapping WAL FILES

From: Janardhana Reddy <jana-reddy(at)mediaring(dot)com(dot)sg>
To: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, janareddy <jana-reddy(at)mediaring(dot)com(dot)sg>
Subject: PERFORMANCE IMPROVEMENT by mapping WAL FILES
Date: 2001-09-26 11:23:27
Message-ID: 3BB1BAAF.256C3DDB@mediaring.com.sg (view raw or flat)
Thread:
Lists: pgsql-hackers
Hi all,
          By   mapping  the WAL files by each backend  in to its address
space  using "mmap"  system call , there  will be  big
 improvements  in performance  from the following point of view:
              1.   Each  backend directly writes in to the address
space  which is  obtained by  maping  the WAL files.
                      this  saves  the write system call at the  end of
every transaction  which transfres  8k of
                      data from user space to kernel.
               2.   since every transaction does not modify all the 8k
content of WAL page , so by issuing the
                       fsync , the  kernel  only   transfers only the
kernel pages which are modified , which is  4k for
                        linux so fsync time  is saved by  twice.
Any comments ?.


Regards
jana

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