gentoo linux, kernel 3.10.31 mount options bug?

gentoo linux, kernel 3.10.31 mount options bug?

[Marko Weber|8000]

hello list,

i have a question about mount options.

at first my fstab:

/dev/md0                /boot           xfs             noauto,noatime  
1 2
/dev/md2                /               xfs             
noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep      
0 1
/dev/md1                /tmp            xfs             
noexec,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep 
       0 1
/dev/VolGroup01/var-www /var/www        xfs             
noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep      
0 1
/dev/VolGroup01/var-log /var/log        xfs             
noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep      
0 1
/dev/VolGroup01/var-lib-mysql   /var/lib/mysql  xfs             
noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep      
0 1
/dev/sda5               none            swap            sw,pri=1         
        0 0
/dev/sdb5               none            swap            sw,pri=2         
        0 0

(YES!, normally i use Label or UUID..... but this is only a test 
machine.....)


AFTER reboot "mount" shows this:

rootfs on / type rootfs (rw)
/dev/root on / type xfs 
(rw,noatime,nodiratime,attr2,nobarrier,inode64,noquota)
/dev/md1 on /tmp type xfs 
(rw,noexec,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)
/dev/mapper/VolGroup01-var--www on /var/www type xfs 
(rw,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)
/dev/mapper/VolGroup01-var--log on /var/log type xfs 
(rw,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)
/dev/mapper/VolGroup01-var--lib--mysql on /var/lib/mysql type xfs 
(rw,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)


on /dev/root "discrad" and some other are not shown


when i do a "mount -o remount /"

"mount" shows this:


rootfs on / type rootfs (rw)
/dev/root on / type xfs 
(rw,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)
/dev/md1 on /tmp type xfs 
(rw,noexec,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)
/dev/mapper/VolGroup01-var--www on /var/www type xfs 
(rw,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)
/dev/mapper/VolGroup01-var--log on /var/log type xfs 
(rw,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)
/dev/mapper/VolGroup01-var--lib--mysql on /var/lib/mysql type xfs 
(rw,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)

now,all options from /etc/fstab are listed.
Is this XFS related?

Kernel 3.10.31
Grub2

in the /etc/grub.d/40_custom i have set:


menuentry "gentoo linux 3.10.31" {
insmod xfs
insmod mdraid09
insmod mdraid1x
insmod lvm
set root=(hd0,2)
linux /bzImage-3.10.31 root=/dev/md2 elevator=cfq clocksource=hpet 
cgroup_disable=memory
}


If you need any more info, let me know.

thnaks for any tipps or answers

marko

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Re: gentoo linux, kernel 3.10.31 mount options bug?

[Eric Sandeen]

On 2/23/14, 3:37 AM, Marko Weber|8000 wrote:
> 
> 
> hello list,
> 
> i have a question about mount options.
> 
> at first my fstab:
> 
> /dev/md0                /boot           xfs             noauto,noatime  1 2
> /dev/md2                /               xfs             noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep      0 1

I guess I won't ask why you decided to tweak all those knobs...

<snip>

> (YES!, normally i use Label or UUID..... but this is only a test machine.....)
> 
> 
> AFTER reboot "mount" shows this:
> 
> rootfs on / type rootfs (rw)
> /dev/root on / type xfs (rw,noatime,nodiratime,attr2,nobarrier,inode64,noquota)

<snip>

default mount options

> 
> on /dev/root "discrad" and some other are not shown
> 
> 
> when i do a "mount -o remount /"
> 
> "mount" shows this:
> 
> 
> rootfs on / type rootfs (rw)
> /dev/root on / type xfs (rw,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)
> /dev/md1 on /tmp type xfs (rw,noexec,noatime,nodiratime,nobarrier,largeio,discard,logbsize=256k,noikeep)

tweaked options.

<snip>

> 
> now,all options from /etc/fstab are listed.
> Is this XFS related?

Not really.  Only some xfs options are remountable, so unless you originally mounted with, say, "largeio" the option won't be in effect.  Mount -o remount won't enable it.  So if you really want all those options enabled on your root fs, you'll need to have them in your initrd/initramfs so that the original mount of the root fs at boot time includes them.

Also, mount may be looking at /etc/mtab rather than /proc/mounts.  /proc/mounts contains the true state of the fileystem w.r.t. mount options.  /etc/mtab is managed by mount, and knows nothing about what the filesystem actually did:

[root@sandeen ~]# mount -o remount,notanoption /home

[root@sandeen ~]# mount | grep home
/dev/md2 on /home type xfs (rw,notanoption)

[root@sandeen ~]# grep home /proc/mounts
/dev/md2 /home xfs rw,seclabel,relatime,attr2,delaylog,noquota 0 0

-Eric


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Re: gentoo linux, kernel 3.10.31 mount options bug?

[Stan Hoeppner]

On 2/23/2014 3:37 AM, Marko Weber|8000 wrote:
...
> linux /bzImage-3.10.31 root=/dev/md2 elevator=cfq clocksource=hpet
                                       ^^^^^^^^^^^^

cfq tends to defeat much of the parallelism in XFS, decreasing
throughput substantially.  This is documented in the XFS FAQ and has
been discussed here many times in the past.  It has been recommended for
a few years now that XFS not be used with the cfq elevator.  Use
deadline with md arrays on plain HBAs and noop on SSDs or any device
with [F|B]BWC, i.e. RAID HBA or SAN controller.

If you're using cfq to allow shaping of per process IO with control
groups, simply using cfq alone may slow down XFS throughput to the point
that you don't need to bother with control group optimizations.

-- 
Stan

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Re: gentoo linux, kernel 3.10.31 mount options bug?

[Marko Weber|8000]

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Thanks for the short and clear answer stan.

Marko

On 23. Februar 2014 23:10:43 MEZ, Stan Hoeppner <stan@hardwarefreak.com> wrote:
>On 2/23/2014 3:37 AM, Marko Weber|8000 wrote:
>...
>> linux /bzImage-3.10.31 root=/dev/md2 elevator=cfq clocksource=hpet
>                                       ^^^^^^^^^^^^
>
>cfq tends to defeat much of the parallelism in XFS, decreasing
>throughput substantially.  This is documented in the XFS FAQ and has
>been discussed here many times in the past.  It has been recommended
>for
>a few years now that XFS not be used with the cfq elevator.  Use
>deadline with md arrays on plain HBAs and noop on SSDs or any device
>with [F|B]BWC, i.e. RAID HBA or SAN controller.
>
>If you're using cfq to allow shaping of per process IO with control
>groups, simply using cfq alone may slow down XFS throughput to the
>point
>that you don't need to bother with control group optimizations.
>
>-- 
>Stan

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