Commit 2544af03 authored by Matteo Croce's avatar Matteo Croce Committed by David S. Miller
Browse files

net: avoid indirect calls in L4 checksum calculation 



Commit 283c16a2 ("indirect call wrappers: helpers to speed-up
indirect calls of builtin") introduces some macros to avoid doing
indirect calls.

Use these helpers to remove two indirect calls in the L4 checksum
calculation for devices which don't have hardware support for it.

As a test I generate packets with pktgen out to a dummy interface
with HW checksumming disabled, to have the checksum calculated in
every sent packet.
The packet rate measured with an i7-6700K CPU and a single pktgen
thread raised from 6143 to 6608 Kpps, an increase by 7.5%

Suggested-by: default avatarDavide Caratti <dcaratti@redhat.com>
Signed-off-by: default avatarMatteo Croce <mcroce@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5ee907f7

net/core/skbuff.c

+11 −4
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ 
#include <linux/highmem.h>

#include <linux/capability.h>

#include <linux/user_namespace.h>

#include <linux/indirect_call_wrapper.h>



#include "datagram.h"
@@ -2507,7 +2508,8 @@ __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, 
	if (copy > 0) {

		if (copy > len)

			copy = len;

		csum = ops->update(skb->data + offset, copy, csum);

		csum = INDIRECT_CALL_1(ops->update, csum_partial_ext,

				       skb->data + offset, copy, csum);

		if ((len -= copy) == 0)

			return csum;

		offset += copy;
@@ -2534,9 +2536,13 @@ __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, 
					      frag->page_offset + offset - start,

					      copy, p, p_off, p_len, copied) {

				vaddr = kmap_atomic(p);

				csum2 = ops->update(vaddr + p_off, p_len, 0);

				csum2 = INDIRECT_CALL_1(ops->update,

							csum_partial_ext,

							vaddr + p_off, p_len, 0);

				kunmap_atomic(vaddr);

				csum = ops->combine(csum, csum2, pos, p_len);

				csum = INDIRECT_CALL_1(ops->combine,

						       csum_block_add_ext, csum,

						       csum2, pos, p_len);

				pos += p_len;

			}
@@ -2559,7 +2565,8 @@ __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, 
				copy = len;

			csum2 = __skb_checksum(frag_iter, offset - start,

					       copy, 0, ops);

			csum = ops->combine(csum, csum2, pos, copy);

			csum = INDIRECT_CALL_1(ops->combine, csum_block_add_ext,

					       csum, csum2, pos, copy);

			if ((len -= copy) == 0)

				return csum;

			offset += copy;

CRA Git | Maintained and supported by SUSTech CRA and CCSE