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69303cafbe
tcp_defer_handler() performs a potentially expensive linear scan of the connection table. So, to mitigate the cost of that we skip if if we're not under at least moderate pressure: either 30% of available connections or 30% (estimated) of available fds used. But, the calculation for this has been broken since it was introduced: we calculate "max_conns" based on c->tcp.conn_count, not TCP_MAX_CONNS, meaning we only exit early if conn_count is less than 30% of itself, i.e. never. If that calculation is "corrected" to be based on TCP_MAX_CONNS, it completely tanks the TCP CRR times for passt - from ~60ms to >1000ms on my laptop. My guess is that this is because in the case of many short lived connections, we're letting the table become much fuller before compacting it. That means that other places which perform a table scan now have to do much, much more. For the time being, simply remove the tests, since they're not doing anything useful. We can reintroduce them more carefully if we see a need for them. This also removes the only user of c->tcp.splice_conn_count, so that can be removed as well. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
79 lines
2.4 KiB
C
79 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later
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* Copyright (c) 2021 Red Hat GmbH
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* Author: Stefano Brivio <sbrivio@redhat.com>
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*/
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#ifndef TCP_H
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#define TCP_H
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#define TCP_TIMER_INTERVAL 1000 /* ms */
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#define TCP_CONN_INDEX_BITS 17 /* 128k - 1 */
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#define TCP_MAX_CONNS MAX_FROM_BITS(TCP_CONN_INDEX_BITS)
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struct ctx;
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void tcp_timer_handler(struct ctx *c, union epoll_ref ref);
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void tcp_listen_handler(struct ctx *c, union epoll_ref ref,
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const struct timespec *now);
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void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events);
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int tcp_tap_handler(struct ctx *c, int af, const void *saddr, const void *daddr,
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const struct pool *p, const struct timespec *now);
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int tcp_sock_init(const struct ctx *c, sa_family_t af, const void *addr,
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const char *ifname, in_port_t port);
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int tcp_init(struct ctx *c);
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void tcp_timer(struct ctx *c, const struct timespec *ts);
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void tcp_defer_handler(struct ctx *c);
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void tcp_sock_set_bufsize(const struct ctx *c, int s);
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void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s);
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/**
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* union tcp_epoll_ref - epoll reference portion for TCP connections
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* @index: Index of connection in table
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* @u32: Opaque u32 value of reference
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*/
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union tcp_epoll_ref {
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uint32_t index:20;
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uint32_t u32;
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};
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/**
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* union tcp_listen_epoll_ref - epoll reference portion for TCP listening
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* @port: Port number we're forwarding *to* (listening port plus delta)
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* @ns: True if listening within the pasta namespace
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* @u32: Opaque u32 value of reference
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*/
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union tcp_listen_epoll_ref {
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struct {
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in_port_t port;
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bool ns;
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};
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uint32_t u32;
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};
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/**
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* struct tcp_ctx - Execution context for TCP routines
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* @hash_secret: 128-bit secret for hash functions, ISN and hash table
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* @conn_count: Count of total connections in connection table
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* @port_to_tap: Ports bound host-side, packets to tap or spliced
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* @fwd_in: Port forwarding configuration for inbound packets
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* @fwd_out: Port forwarding configuration for outbound packets
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* @timer_run: Timestamp of most recent timer run
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* @kernel_snd_wnd: Kernel reports sending window (with commit 8f7baad7f035)
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* @pipe_size: Size of pipes for spliced connections
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*/
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struct tcp_ctx {
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uint64_t hash_secret[2];
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int conn_count;
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struct port_fwd fwd_in;
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struct port_fwd fwd_out;
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struct timespec timer_run;
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#ifdef HAS_SND_WND
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int kernel_snd_wnd;
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#endif
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size_t pipe_size;
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};
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#endif /* TCP_H */
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