Re: [PATCH 32/32] ext4: add nombcache mount option

2017-06-22 Thread Theodore Ts'o
On Wed, Jun 21, 2017 at 06:49:39PM -0700, Tahsin Erdogan wrote: > The main purpose of mb cache is to achieve deduplication in > extended attributes. In use cases where opportunity for deduplication > is unlikely, it only adds overhead. > > Add a mount option to explicitly turn off mb cache. > >

Re: [PATCH 32/32] ext4: add nombcache mount option

2017-06-22 Thread Theodore Ts'o
On Wed, Jun 21, 2017 at 06:49:39PM -0700, Tahsin Erdogan wrote: > The main purpose of mb cache is to achieve deduplication in > extended attributes. In use cases where opportunity for deduplication > is unlikely, it only adds overhead. > > Add a mount option to explicitly turn off mb cache. > >

Re: [PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Theodore Ts'o
On Wed, Jun 21, 2017 at 04:46:48PM -0700, Tahsin Erdogan wrote: > Remount option handling is a bit strange. If an option is not > specified, it is not automatically cleared in sbi->s_mount_opt. So, > once nombcache option is set in the original mount, it is not possible > to clear it. I don't know

Re: [PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Theodore Ts'o
On Wed, Jun 21, 2017 at 04:46:48PM -0700, Tahsin Erdogan wrote: > Remount option handling is a bit strange. If an option is not > specified, it is not automatically cleared in sbi->s_mount_opt. So, > once nombcache option is set in the original mount, it is not possible > to clear it. I don't know

[PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Tahsin Erdogan
The main purpose of mb cache is to achieve deduplication in extended attributes. In use cases where opportunity for deduplication is unlikely, it only adds overhead. Add a mount option to explicitly turn off mb cache. Suggested-by: Andreas Dilger Signed-off-by: Tahsin Erdogan

[PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Tahsin Erdogan
The main purpose of mb cache is to achieve deduplication in extended attributes. In use cases where opportunity for deduplication is unlikely, it only adds overhead. Add a mount option to explicitly turn off mb cache. Suggested-by: Andreas Dilger Signed-off-by: Tahsin Erdogan --- v2: -

Re: [PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Tahsin Erdogan
>> + if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_NO_MBCACHE) >> { >> + ext4_msg(sb, KERN_ERR, "can't enable nombcache during >> remount"); >> + err = -EINVAL; >> + goto restore_opts; >> + } > > It appears that this restriction also

Re: [PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Tahsin Erdogan
>> + if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_NO_MBCACHE) >> { >> + ext4_msg(sb, KERN_ERR, "can't enable nombcache during >> remount"); >> + err = -EINVAL; >> + goto restore_opts; >> + } > > It appears that this restriction also

[PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Tahsin Erdogan
The main purpose of mb cache is to achieve deduplication in extended attributes. In use cases where opportunity for deduplication is unlikely, it only adds overhead. Add a mount option to explicitly turn off mb cache. Suggested-by: Andreas Dilger Signed-off-by: Tahsin Erdogan

[PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Tahsin Erdogan
The main purpose of mb cache is to achieve deduplication in extended attributes. In use cases where opportunity for deduplication is unlikely, it only adds overhead. Add a mount option to explicitly turn off mb cache. Suggested-by: Andreas Dilger Signed-off-by: Tahsin Erdogan ---

Re: [PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Andreas Dilger
On Jun 20, 2017, at 3:14 AM, Tahsin Erdogan wrote: > > The main purpose of mb cache is to achieve deduplication in > extended attributes. In use cases where opportunity for deduplication > is unlikely, it only adds overhead. > > Add a mount option to explicitly turn off mb

Re: [PATCH 32/32] ext4: add nombcache mount option

2017-06-21 Thread Andreas Dilger
On Jun 20, 2017, at 3:14 AM, Tahsin Erdogan wrote: > > The main purpose of mb cache is to achieve deduplication in > extended attributes. In use cases where opportunity for deduplication > is unlikely, it only adds overhead. > > Add a mount option to explicitly turn off mb cache. > >

[PATCH 32/32] ext4: add nombcache mount option

2017-06-20 Thread Tahsin Erdogan
The main purpose of mb cache is to achieve deduplication in extended attributes. In use cases where opportunity for deduplication is unlikely, it only adds overhead. Add a mount option to explicitly turn off mb cache. Suggested-by: Andreas Dilger Signed-off-by: Tahsin Erdogan

[PATCH 32/32] ext4: add nombcache mount option

2017-06-20 Thread Tahsin Erdogan
The main purpose of mb cache is to achieve deduplication in extended attributes. In use cases where opportunity for deduplication is unlikely, it only adds overhead. Add a mount option to explicitly turn off mb cache. Suggested-by: Andreas Dilger Signed-off-by: Tahsin Erdogan ---