Bug #51786 Set VX_CONCURRENT cache advisory for VxFS
Submitted: 6 Mar 2010 2:33 Modified: 6 Mar 2010 8:43
Reporter: River Tarnell Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: InnoDB storage engine Severity:S4 (Feature request)
Version:5.1.44 OS:Any
Assigned to: CPU Architecture:Any

[6 Mar 2010 2:33] River Tarnell 
Description:
When InnoDB data files are on a VxFS filesystem, performance can be significantly improved by setting the VX_CONCURRENT cache advisory on the file:

#include <sys/fs/vx_ioctl.h>
ioctl(fd, VX_SETCACHE, VX_CONCURRENT);

This enables both direct i/o (O_DIRECT), and concurrent i/o on the file (meaning writes aren't serialised).

The same effect can be achieved with the 'cio' mount option, but since this disables the OS page cache for all files, it hurts MyISAM performance.

How to repeat:
Use InnoDB on VxFS.  Notice that performance is degraded because writes are buffered and serialised.
[6 Mar 2010 8:43] Valeriy Kravchuk 
Thank you for the feature request.