[ovs-dev] [PATCH] datapath: Increase maximum allocation size of action list.

Jesse Gross jesse at nicira.com
Mon Feb 25 18:58:53 UTC 2013


On Mon, Feb 25, 2013 at 10:51 AM, Ben Pfaff <blp at nicira.com> wrote:
> On Fri, Feb 22, 2013 at 12:28:14PM -0800, Jesse Gross wrote:
>> The switch to flow based tunneling increased the size of each output
>> action in the flow action list.  In extreme cases, this can result
>> in the action list exceeding the maximum buffer size.
>>
>> This doubles the maximum buffer size to compensate for the increase
>> in action size.  Since the buffer is potentially very large, it also
>> switches to vmalloc.  In the common case, most allocations will be
>> less than a page and vmalloc automatically uses kmalloc in that case.
>> Therefore, for the majority of situations, this will have no impact.
>>
>> Bug #15203
>>
>> Signed-off-by: Jesse Gross <jesse at nicira.com>
>
> Are you sure that vmalloc() automatically uses kmalloc() for small
> allocations?  Looking at 2.6.32 and 3.2, it appears to me that even
> vmalloc(1) actually allocates at least 2 pages plus a small control
> block.

No, I was wrong about that.  Pravin updated and fixed this patch,
which has already been applied.



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