Re: [Qemu-devel] [PATCH qemu v3 01/13] memory: Postpone flatview and dispatch tree building till all devices are added

[Paolo Bonzini]

On 19/09/2017 08:57, Alexey Kardashevskiy wrote:
>>> 2) also, after patch 2 you know that the address space has no listeners
>>> here, so the begin/commit isn't really needed.  Instead you can use the
>>> open-coded loop to directly generate the FlatView.  This avoids touching
>>> _all_ address spaces, which is already an improvement from O(n^2) to
>>> O(n) rebuilds on device startup.
> 03/13 does this already, no?
> 

No, there's still

    as->dispatch = NULL;
    memory_region_update_pending |= root->enabled;
    memory_region_transaction_commit();

when creating the address space, which touches all address spaces.

Paolo