Re: [PATCH v5 04/10] xen/blkfront: split per device io_lock

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Sat, Nov 14, 2015 at 11:12:13AM +0800, Bob Liu wrote:
> After commit "xen/blkfront: separate per ring information out of device
> info", per-ring data is protected by a per-device lock('io_lock').
> 
> This is not a good way and will effect the scalability, so introduces a
> per-ring lock('ring_lock').
> 
> The old 'io_lock' is renamed to 'dev_lock' which protects the ->grants list and
> persistent_gnts_c shared by all rings.

I changed the description a bit:

    xen/blkfront: split per device io_lock
    
    After patch "xen/blkfront: separate per ring information out of device
    info", per-ring data is protected by a per-device lock ('io_lock').
    
    This is not a good way and will effect the scalability, so introduce a
    per-ring lock ('ring_lock').
    
    The old 'io_lock' is renamed to 'dev_lock' which protects the ->grants list and
    ->persistent_gnts_c which are shared by all rings.
    
    Note that in 'blkfront_probe' the 'blkfront_info' is setup via kzalloc
    so setting ->persistent_gnts_c to zero is not needed.