Re: [dm-devel] mirrored device with thousand of mappingtableentries

[Zdenek Kabelac <zkabelac redhat com>]

Dne 7.3.2011 03:59, Martin K. Petersen napsal(a):
>>>>>> "Zdenek" == Zdenek Kabelac <zkabelac redhat com> writes:
> 
> Zdenek> My finding seems to show that BIP-256 slabtop segment grow by
> Zdenek> ~73KB per each device (while dm-io is ab out ~26KB)
> 
> Ok, I see it now that I tried with a bunch of DM devices.
> 
> DM allocates a bioset per volume. And since each bioset has an integrity
> mempool you'll end up with a bunch of memory locked down. It seems like
> a lot but it's actually the same amount as we reserve for the data path
> (bio-0 + biovec-256).
> 
> Since a bioset is not necessarily tied to a single block device we can't
> automatically decide whether to allocate the integrity pool or not. In
> the DM case, however, we just set up the integrity profile so the
> information is available.
> 
> Can you please try the following patch? This will change things so we
> only attach an integrity pool to the bioset if the logical volume is
> integrity-capable.
> 

Yep - patch seems to fix the problem with wasted memory.

Thanks

tested-by: zkabelac redhat com