[ovs-dev] [mask array v2] datapath: keep mask array compact when deleting mask

[Pravin Shelar]

I will review it by tomorrow.

On Thu, May 29, 2014 at 2:08 PM, Ben Pfaff <blp at nicira.com> wrote:
> This has been sitting in patchwork for a while. I guess that Pravin or
> Jesse needs to review it?
>
> On Fri, May 16, 2014 at 5:33 PM, Andy Zhou <azhou at nicira.com> wrote:
>> When deleting a mask from the mask array, we always move the last entry
>> into its current location. Another approach can be NULL in its current
>> place, and periodically compact it.
>>
>> The approach taken by this patch is more efficient during run time.
>> During look up, fast path packet don't have to skip over NULL pointers.
>>
>> A more important advantage of this approach is that it tries to
>> keep the mask array index stable by avoiding periodic index reshuffle.
>>
>> This patch implements an optimization to further promote index
>> stability.  By leaving the last entry value intact when moving it to
>> a new location, the old cache index can 'fix' themselves, by noticing
>> the index in the cache is outside the valid mask array region. The new
>> index can be found by scanning the mask pointer within the valid region.
>>
>> Signed-off-by: Andy Zhou <azhou at nicira.com>