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be represented: - A single policy namespace is defined, consisting of four possible policies: "default" to use the global default, "deferred" to force deferred dispatch, "direct" to employ direct dispatch where possible, and "hybrid" which makes a dynamic decision based on CPU affinity, ordering, etc. Routines are implemented to convert between strings and an integer namespace. - A new global variable, netisr_dispatch_policy, subsumes existing global variables for direct dispatch, forced direct dispatch, etc, and is used for explicit policy interpretation and composition. Old variables remain so that they can be exported by legacy sysctls for use by old netstat(1) binaries. A new sysctl and tunable, netisr.dispatch.policy, accepts the above strings for specifying a global policy default. - The protocol registration structure, netisr_handler, grows an nh_dispatch field, which accepts a per-policy policy override. The default value is '0', which corresponds to "default", meaning that protocols will accept the global default policy unless otherwise specified. - Policies are now interpreted and composed explicitly at various points in packet dispatch; protocol policies override global policies. - Protocols grow the ability to express a non-opinion about affinity even when implenting m2cpuid by returning NETISR_CPUID_NONE. In that case, the framework falls back on source ordering, rather than simply using the current CPU. These changes are in support of allowing link layer re-dispatch based on RSS or similar hashes provided by NICs, especially in the case where the number of hardware receive queues matches hardware core count, rather than hardware thread count, requiring further software redistributeon. (i.e., on RMI XLR). MFC after: 3 weeks Reviewed by: bz Sponsored by: Juniper Networks, Inc.
248 lines
9.2 KiB
C
248 lines
9.2 KiB
C
/*-
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* Copyright (c) 2007-2009 Robert N. M. Watson
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* Copyright (c) 2010-2011 Juniper Networks, Inc.
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* All rights reserved.
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*
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* This software was developed by Robert N. M. Watson under contract
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* to Juniper Networks, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _NET_NETISR_H_
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#define _NET_NETISR_H_
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/*
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* The netisr (network interrupt service routine) provides a deferred
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* execution evironment in which (generally inbound) network processing can
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* take place. Protocols register handlers which will be executed directly,
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* or via deferred dispatch, depending on the circumstances.
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*
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* Historically, this was implemented by the BSD software ISR facility; it is
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* now implemented via a software ithread (SWI).
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*/
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/*
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* Protocol numbers, which are encoded in monitoring applications and kernel
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* modules. Internally, these are used in bit shift operations so must have
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* a value 0 < proto < 32; we currently further limit at compile-time to 16
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* for array-sizing purposes.
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*/
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#define NETISR_IP 1
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#define NETISR_IGMP 2 /* IGMPv3 output queue */
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#define NETISR_ROUTE 3 /* routing socket */
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#define NETISR_AARP 4 /* Appletalk ARP */
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#define NETISR_ATALK2 5 /* Appletalk phase 2 */
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#define NETISR_ATALK1 6 /* Appletalk phase 1 */
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#define NETISR_ARP 7 /* same as AF_LINK */
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#define NETISR_IPX 8 /* same as AF_IPX */
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#define NETISR_ETHER 9 /* ethernet input */
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#define NETISR_IPV6 10
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#define NETISR_NATM 11
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#define NETISR_EPAIR 12 /* if_epair(4) */
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/*
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* Protocol ordering and affinity policy constants. See the detailed
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* discussion of policies later in the file.
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*/
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#define NETISR_POLICY_SOURCE 1 /* Maintain source ordering. */
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#define NETISR_POLICY_FLOW 2 /* Maintain flow ordering. */
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#define NETISR_POLICY_CPU 3 /* Protocol determines CPU placement. */
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/*
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* Protocol dispatch policy constants; selects whether and when direct
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* dispatch is permitted.
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*/
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#define NETISR_DISPATCH_DEFAULT 0 /* Use global default. */
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#define NETISR_DISPATCH_DEFERRED 1 /* Always defer dispatch. */
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#define NETISR_DISPATCH_HYBRID 2 /* Allow hybrid dispatch. */
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#define NETISR_DISPATCH_DIRECT 3 /* Always direct dispatch. */
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/*
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* Monitoring data structures, exported by sysctl(2).
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*
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* Three sysctls are defined. First, a per-protocol structure exported by
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* net.isr.proto.
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*/
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#define NETISR_NAMEMAXLEN 32
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struct sysctl_netisr_proto {
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u_int snp_version; /* Length of struct. */
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char snp_name[NETISR_NAMEMAXLEN]; /* nh_name */
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u_int snp_proto; /* nh_proto */
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u_int snp_qlimit; /* nh_qlimit */
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u_int snp_policy; /* nh_policy */
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u_int snp_flags; /* Various flags. */
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u_int snp_dispatch; /* Dispatch policy. */
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u_int _snp_ispare[6];
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};
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/*
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* Flags for sysctl_netisr_proto.snp_flags.
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*/
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#define NETISR_SNP_FLAGS_M2FLOW 0x00000001 /* nh_m2flow */
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#define NETISR_SNP_FLAGS_M2CPUID 0x00000002 /* nh_m2cpuid */
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#define NETISR_SNP_FLAGS_DRAINEDCPU 0x00000004 /* nh_drainedcpu */
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/*
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* Next, a structure per-workstream, with per-protocol data, exported as
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* net.isr.workstream.
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*/
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struct sysctl_netisr_workstream {
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u_int snws_version; /* Length of struct. */
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u_int snws_flags; /* Various flags. */
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u_int snws_wsid; /* Workstream ID. */
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u_int snws_cpu; /* nws_cpu */
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u_int _snws_ispare[12];
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};
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/*
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* Flags for sysctl_netisr_workstream.snws_flags
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*/
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#define NETISR_SNWS_FLAGS_INTR 0x00000001 /* nws_intr_event */
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/*
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* Finally, a per-workstream-per-protocol structure, exported as
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* net.isr.work.
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*/
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struct sysctl_netisr_work {
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u_int snw_version; /* Length of struct. */
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u_int snw_wsid; /* Workstream ID. */
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u_int snw_proto; /* Protocol number. */
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u_int snw_len; /* nw_len */
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u_int snw_watermark; /* nw_watermark */
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u_int _snw_ispare[3];
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uint64_t snw_dispatched; /* nw_dispatched */
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uint64_t snw_hybrid_dispatched; /* nw_hybrid_dispatched */
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uint64_t snw_qdrops; /* nw_qdrops */
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uint64_t snw_queued; /* nw_queued */
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uint64_t snw_handled; /* nw_handled */
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uint64_t _snw_llspare[7];
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};
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#ifdef _KERNEL
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/*-
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* Protocols express ordering constraints and affinity preferences by
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* implementing one or neither of nh_m2flow and nh_m2cpuid, which are used by
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* netisr to determine which per-CPU workstream to assign mbufs to.
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*
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* The following policies may be used by protocols:
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*
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* NETISR_POLICY_SOURCE - netisr should maintain source ordering without
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* advice from the protocol. netisr will ignore any
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* flow IDs present on the mbuf for the purposes of
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* work placement.
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*
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* NETISR_POLICY_FLOW - netisr should maintain flow ordering as defined by
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* the mbuf header flow ID field. If the protocol
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* implements nh_m2flow, then netisr will query the
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* protocol in the event that the mbuf doesn't have a
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* flow ID, falling back on source ordering.
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*
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* NETISR_POLICY_CPU - netisr will delegate all work placement decisions to
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* the protocol, querying nh_m2cpuid for each packet.
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*
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* Protocols might make decisions about work placement based on an existing
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* calculated flow ID on the mbuf, such as one provided in hardware, the
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* receive interface pointed to by the mbuf (if any), the optional source
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* identifier passed at some dispatch points, or even parse packet headers to
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* calculate a flow. Both protocol handlers may return a new mbuf pointer
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* for the chain, or NULL if the packet proves invalid or m_pullup() fails.
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*
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* XXXRW: If we eventually support dynamic reconfiguration, there should be
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* protocol handlers to notify them of CPU configuration changes so that they
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* can rebalance work.
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*/
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struct mbuf;
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typedef void netisr_handler_t(struct mbuf *m);
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typedef struct mbuf *netisr_m2cpuid_t(struct mbuf *m, uintptr_t source,
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u_int *cpuid);
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typedef struct mbuf *netisr_m2flow_t(struct mbuf *m, uintptr_t source);
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typedef void netisr_drainedcpu_t(u_int cpuid);
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#define NETISR_CPUID_NONE ((u_int)-1) /* No affinity returned. */
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/*
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* Data structure describing a protocol handler.
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*/
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struct netisr_handler {
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const char *nh_name; /* Character string protocol name. */
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netisr_handler_t *nh_handler; /* Protocol handler. */
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netisr_m2flow_t *nh_m2flow; /* Query flow for untagged packet. */
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netisr_m2cpuid_t *nh_m2cpuid; /* Query CPU to process mbuf on. */
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netisr_drainedcpu_t *nh_drainedcpu; /* Callback when drained a queue. */
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u_int nh_proto; /* Integer protocol ID. */
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u_int nh_qlimit; /* Maximum per-CPU queue depth. */
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u_int nh_policy; /* Work placement policy. */
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u_int nh_dispatch; /* Dispatch policy. */
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u_int nh_ispare[4]; /* For future use. */
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void *nh_pspare[4]; /* For future use. */
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};
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/*
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* Register, unregister, and other netisr handler management functions.
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*/
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void netisr_clearqdrops(const struct netisr_handler *nhp);
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void netisr_getqdrops(const struct netisr_handler *nhp,
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u_int64_t *qdropsp);
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void netisr_getqlimit(const struct netisr_handler *nhp, u_int *qlimitp);
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void netisr_register(const struct netisr_handler *nhp);
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int netisr_setqlimit(const struct netisr_handler *nhp, u_int qlimit);
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void netisr_unregister(const struct netisr_handler *nhp);
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/*
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* Process a packet destined for a protocol, and attempt direct dispatch.
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* Supplemental source ordering information can be passed using the _src
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* variant.
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*/
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int netisr_dispatch(u_int proto, struct mbuf *m);
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int netisr_dispatch_src(u_int proto, uintptr_t source, struct mbuf *m);
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int netisr_queue(u_int proto, struct mbuf *m);
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int netisr_queue_src(u_int proto, uintptr_t source, struct mbuf *m);
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/*
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* Provide a default implementation of "map an ID to a CPU ID".
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*/
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u_int netisr_default_flow2cpu(u_int flowid);
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/*
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* Utility routines to return the number of CPUs participting in netisr, and
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* to return a mapping from a number to a CPU ID that can be used with the
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* scheduler.
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*/
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u_int netisr_get_cpucount(void);
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u_int netisr_get_cpuid(u_int cpunumber);
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/*
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* Interfaces between DEVICE_POLLING and netisr.
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*/
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void netisr_sched_poll(void);
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void netisr_poll(void);
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void netisr_pollmore(void);
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#endif /* !_KERNEL */
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#endif /* !_NET_NETISR_H_ */
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