Re: adding proper O_SYNC/O_DSYNC, was Re: O_DIRECT and barriers

From: Jamie Lokier
Date: Fri Aug 28 2009 - 19:06:49 EST


Christoph Hellwig wrote:
> - given that our current O_SYNC really is and always has been actuall
> Posix O_DSYNC

Are you sure about this?

>From http://www-01.ibm.com/support/docview.wss?uid=isg1IZ01704 :

Error description

LINUX O_DIRECT/O_SYNC TAKES TOO MANY IOS

Problem summary

On AIX, the O_SYNC and O_DSYNC are different values and
performance improvement are available because the inode does
not need to be flushed for mtime changes only.
On Linux the flags are the same, so performance is lost.
when databases open files with O_DIRECT and O_SYNC.

-- Jamie
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