svn commit: r256956 - in head/sys: cam/ata cam/scsi cddl/contrib/opensolaris/uts/common/fs/zfs cddl/contrib/opensolaris/uts/common/fs/zfs/sys geom sys

[Slawa Olhovchenkov]

On Thu, Oct 24, 2013 at 12:00:54PM +0100, Steven Hartland wrote:

> Not familiar with that option, but having a quick look in src
> it doesn't seem to be FS specific, seems to be handled by vfs.

VFS set options include this (in high bits).
This options next passed to FS code (.vop_read = zfs_freebsd_read), in
FS(zfs) code options filtered:

return (zfs_read(ap->a_vp, ap->a_uio, ioflags(ap->a_ioflag),
            ap->a_cred, NULL));

ioflags(int ioflags)
{
        int flags = 0;

        if (ioflags & IO_APPEND)
                flags |= FAPPEND;
        if (ioflags & IO_NDELAY)
                flags |= FNONBLOCK;
        if (ioflags & IO_SYNC)
                flags |= (FSYNC | FDSYNC | FRSYNC);

        return (flags);
}

and we lost FRDAHEAD/ADVISE hints, IO_DIRECT, IO_INVAL and so.

> Can anyone confirm or deny this?
> 
> ----- Original Message ----- 
> From: "Slawa Olhovchenkov" <slw at zxy.spb.ru>
> 
> 
> > On Wed, Oct 23, 2013 at 09:54:59AM +0000, Steven Hartland wrote:
> > 
> >> Author: smh
> >> Date: Wed Oct 23 09:54:58 2013
> >> New Revision: 256956
> >> URL: http://svnweb.freebsd.org/changeset/base/256956
> >> 
> >> Log:
> >>   Improve ZFS N-way mirror read performance by using load and locality
> >>   information.
> > 
> > What about support F_READAHEAD in ZFS (with prefetch disabled by
> > CPU-intensive)?
> >
> 
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