[lvm-devel] [PATCH 1/6] Pool locking code

[Zdenek Kabelac]

Dne 23.3.2011 16:13, Joe Thornber napsal(a):
> On Wed, 2011-03-23 at 15:54 +0100, Zdenek Kabelac wrote:
>> Forget to answer the size question -  >8MB is allocated by the VG
>> mempool when
>> set of simple linear 7200LVs on 1 PV are in use.
> 
> So I think each snapshot/restore of a VG pool of that size is going to
> take ~0.1 seconds.  So now my question is how many times are we
> expecting to happen during a typical tool invocation?  Your previous
> reply suggested it happens just once?


If there would be just 1 vg read for 7200 activate call - obviously I'd not
need to play with this dm_pool locking :)

So there is 7200 vg reads - which will use this one locked pool with my patch set:

To give some time info here
(using my unoptimized gcc debug build on C2D 2.2GHz - but with few more
patches applied than current upstream)

Deactivate 7200LV   (7200 already active)
real	1m16.140s
user	0m5.686s
sys	0m31.410s


Deactivate 7200LV (non active)
real	0m2.121s
user	0m1.083s
sys	0m1.032s


Activate 7200  (non active)
real	2m19.324s
user	0m6.503s
sys	1m30.785s

Activate 7200 (7200 already active)
real	0m10.945s
user	0m1.422s
sys	0m9.502s

Zdenek