On Jun 9, 2010, at 11:25 PM, Heikki Linnakangas <heikki.linnakan...@enterprisedb.com
> wrote:
On 10/06/10 06:47, Mark Wong wrote:
I wanted to propose a fix for to xlog.c regarding the use of
posix_fadvise() for 9.1 (unless someone feels it's ok for 9.0).
Currently posix_fadvise() is used right before a log file is closed
so
it's effectively not doing anything, when posix_fadvise is to be
called. This patch moves the posix_fadvise() call into 3 other
locations within XLogFileInit() where a file handle is returned. The
first case is where an existing open file handle is returned. The
next case is when a file is to be zeroed out. The third case is
returning a file handle, which may be the file that was just zeroed
out.
I don't think POSIX_FADV_DONTNEED does what you think it does. It
tells the kernel that "you don't need to keep these pages in the
cache anymore, I won't be accessing them anymore". If you call it
when you open the file, before reading/writing, there is nothing in
the cache and the call will do nothing.
Oops, my bad. I think I was confused by the short description in the
man page. I didn't read the longer descriptoon. :( Then would it be
worth making the this call after the file is zeroed out?
Regards,
Mark
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
