O_DIRECT for WAL writes - Mailing list pgsql-patches

From ITAGAKI Takahiro
Subject O_DIRECT for WAL writes
Date
Msg-id 20050526155748.3D95.ITAGAKI.TAKAHIRO@lab.ntt.co.jp
Whole thread Raw
Responses Re: O_DIRECT for WAL writes
List pgsql-patches
This patch ticks off the following TODO items:
  Consider use of open/fcntl(O_DIRECT) to minimize OS caching, especially for WAL writes.

The patch adds a new choice "open_direct" to wal_sync_method.
It uses O_DIRECT flags for WAL writes, like O_SYNC.


I had sent a patch looked like this before
(http://candle.pha.pa.us/mhonarc/patches2/msg00131.html)
but I found it is not always needed to write multiple pages in one write()
because most disks have writeback-cache. So, I left only O_DIRECT routines
in the patch and it impacts a present source code less.

---
ITAGAKI Takahiro
NTT Cyber Space Laboratories

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