541ea69a90
This patch increases the headroom allocated when using build_skb on a
system with 4K pages. Specifically the breakdown of headroom versus cache
size is as follows:
L1 Cache Size Headroom
64 192
64, NET_IP_ALIGN == 2 194
128 128
128, NET_IP_ALIGN == 2 130
256 512
256, NET_IP_ALIGN == 2 258
I stopped at supporting only a cache line size of 256 as that was the
largest cache size I could find supported in the kernel.
With this we are guaranteeing at least 128 bytes of headroom to spare in
the frame. This should be enough for us to insert a couple of IPv6 headers
if needed which is likely enough room for anything XDP should need.
I'm leaving the padding for systems with pages larger than 4K unmodified
for now. XDP currently isn't really setup to work on those types of
systems so we can cross that bridge when we get there.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.