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@@ -1,96 +0,0 @@
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-From 9208d2863ac689a563b92f2161d8d1e7127d0add Mon Sep 17 00:00:00 2001
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-From: Ilya Ponetayev <[email protected]>
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-Date: Thu, 25 Jun 2020 22:12:07 +0200
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-Subject: [PATCH] sch_cake: don't try to reallocate or unshare skb
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- unconditionally
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-MIME-Version: 1.0
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-Content-Type: text/plain; charset=UTF-8
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-Content-Transfer-Encoding: 8bit
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-
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-cake_handle_diffserv() tries to linearize mac and network header parts of
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-skb and to make it writable unconditionally. In some cases it leads to full
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-skb reallocation, which reduces throughput and increases CPU load. Some
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-measurements of IPv4 forward + NAPT on MIPS router with 580 MHz single-core
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-CPU was conducted. It appears that on kernel 4.9 skb_try_make_writable()
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-reallocates skb, if skb was allocated in ethernet driver via so-called
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-'build skb' method from page cache (it was discovered by strange increase
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-of kmalloc-2048 slab at first).
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-
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-Obtain DSCP value via read-only skb_header_pointer() call, and leave
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-linearization only for DSCP bleaching or ECN CE setting. And, as an
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-additional optimisation, skip diffserv parsing entirely if it is not needed
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-by the current configuration.
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-
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-Fixes: c87b4ecdbe8d ("sch_cake: Make sure we can write the IP header before changing DSCP bits")
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-Signed-off-by: Ilya Ponetayev <[email protected]>
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-[ fix a few style issues, reflow commit message ]
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-Signed-off-by: Toke Høiland-Jørgensen <[email protected]>
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-Signed-off-by: David S. Miller <[email protected]>
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-Signed-off-by: Kevin Darbyshire-Bryant <[email protected]>
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----
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- net/sched/sch_cake.c | 41 ++++++++++++++++++++++++++++++-----------
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- 1 file changed, 30 insertions(+), 11 deletions(-)
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-
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---- a/net/sched/sch_cake.c
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-+++ b/net/sched/sch_cake.c
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-@@ -1553,30 +1553,49 @@ static unsigned int cake_drop(struct Qdi
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-
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- static u8 cake_handle_diffserv(struct sk_buff *skb, u16 wash)
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- {
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-- int wlen = skb_network_offset(skb);
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-+ const int offset = skb_network_offset(skb);
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-+ u16 *buf, buf_;
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- u8 dscp;
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-
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- switch (tc_skb_protocol(skb)) {
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- case htons(ETH_P_IP):
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-- wlen += sizeof(struct iphdr);
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-- if (!pskb_may_pull(skb, wlen) ||
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-- skb_try_make_writable(skb, wlen))
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-+ buf = skb_header_pointer(skb, offset, sizeof(buf_), &buf_);
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-+ if (unlikely(!buf))
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- return 0;
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-
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-- dscp = ipv4_get_dsfield(ip_hdr(skb)) >> 2;
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-- if (wash && dscp)
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-+ /* ToS is in the second byte of iphdr */
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-+ dscp = ipv4_get_dsfield((struct iphdr *)buf) >> 2;
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-+
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-+ if (wash && dscp) {
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-+ const int wlen = offset + sizeof(struct iphdr);
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-+
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-+ if (!pskb_may_pull(skb, wlen) ||
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-+ skb_try_make_writable(skb, wlen))
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-+ return 0;
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-+
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- ipv4_change_dsfield(ip_hdr(skb), INET_ECN_MASK, 0);
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-+ }
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-+
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- return dscp;
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-
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- case htons(ETH_P_IPV6):
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-- wlen += sizeof(struct ipv6hdr);
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-- if (!pskb_may_pull(skb, wlen) ||
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-- skb_try_make_writable(skb, wlen))
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-+ buf = skb_header_pointer(skb, offset, sizeof(buf_), &buf_);
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-+ if (unlikely(!buf))
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- return 0;
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-
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-- dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> 2;
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-- if (wash && dscp)
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-+ /* Traffic class is in the first and second bytes of ipv6hdr */
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-+ dscp = ipv6_get_dsfield((struct ipv6hdr *)buf) >> 2;
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-+
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-+ if (wash && dscp) {
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-+ const int wlen = offset + sizeof(struct ipv6hdr);
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-+
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-+ if (!pskb_may_pull(skb, wlen) ||
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-+ skb_try_make_writable(skb, wlen))
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-+ return 0;
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-+
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- ipv6_change_dsfield(ipv6_hdr(skb), INET_ECN_MASK, 0);
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-+ }
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-+
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- return dscp;
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-
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- case htons(ETH_P_ARP):
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