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

Ben Pfaff blp at nicira.com
Mon Feb 25 18:51:08 UTC 2013


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.



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