Differential D37757 Diff 114511 sys/net/route/route_cache.h

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sys/net/route/route_cache.h

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				/*-
				* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
				*
				* Copyright (c) 2022 Zhenlei Huang
				*
				* Redistribution and use in source and binary forms, with or without
				* modification, are permitted provided that the following conditions
				* are met:
				* 1. Redistributions of source code must retain the above copyright
				* notice, this list of conditions and the following disclaimer.
				* 2. Redistributions in binary form must reproduce the above copyright
				* notice, this list of conditions and the following disclaimer in the
				* documentation and/or other materials provided with the distribution.
				*
				* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
				* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
				* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
				* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
				* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
				* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
				* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
				* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
				* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
				* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
				* SUCH DAMAGE.
				*
				* $FreeBSD$
				*/

				#ifndef _NET_ROUTE_ROUTE_CACHE_H_
				#define _NET_ROUTE_ROUTE_CACHE_H_

				struct route_cache_pcpu {
				struct mtx mtx;
				union {
				struct route ro;
				#ifdef INET
				melifaroUnsubmitted Done Inline Actions Different `struct route` differ only by the tail `struct sockaddr_XX`. I'd consider having a unified structure of everything, sufficient to hold any supported/compiled family. Union inside can be `struct route`, `struct route_in` and `struct route_in6`, with the latter two being conditionally enabled. The former one can be used in most of the internal code, as it doesn't care about the actual sockaddr. melifaro: Different `struct route` differ only by the tail `struct sockaddr_XX`. I'd consider having a…
				zleiAuthorUnsubmitted Done Inline Actions My previous version is exactly struct route_cache_pcpu { struct mtx mtx; union { #ifdef INET struct route ro; #endif #ifdef INET6 struct route_in6 ro6; #endif } } I worried about future change of `struct route_in6` then `route_cache_pcpu` may occupy extra unused cache line then it will punish dual stacked host. And also consumers should include both `opt_inet.h` and `opt_inet6.h` otherwise boom. Anyway that could be solved by exposing pointer `struct route_cache ` rather than the structure but this introduce another hop ( sc->route_cache->pcpu ). For modern CPUs this might be negligible but by I doubt it deserves. Indeed I'm planning to embed `rt_cookie` into `struct route[_in6]` so that route cache can be asynchronously revalidated without waiting on lock ( if trylock fails just ignore and continue, the lock is held by hot data path and will be validated ). Embedding `rt_cookie` into `struct route_in6` then `struct route_cache_pcpu` will need one more cache line on 64bit systems. zlei:* My previous version is exactly ``` struct route_cache_pcpu { struct mtx mtx; union { #ifdef…
				struct route_in ro4;
				#endif
				#ifdef INET6
				struct route_in6 ro6;
				#endif
				};
				} __aligned(CACHE_LINE_SIZE);

				struct route_cache {
				struct route_cache_pcpu *pcpu;
				struct rib_subscription *rs;
				};

				void route_cache_init(struct route_cache *);
				void route_cache_uninit(struct route_cache *);
				void route_cache_invalidate(struct route_cache *);
				void route_cache_subscribe_rib_event(struct route_cache *, int, uint32_t);
				void route_cache_unsubscribe_rib_event(struct route_cache *);

				static inline struct route *
				route_cache_acquire(struct route_cache *rc)
				{
				struct route_cache_pcpu *pcpu;
				zleiAuthorUnsubmitted Done Inline Actions A second thought that if embed `family` and `fibnum` into `struct route_cache` then the implementation will be more simple (and also the usage of APIs). zlei: A second thought that if embed `family` and `fibnum` into `struct route_cache` then the…
				struct route *ro = NULL;

				pcpu = zpcpu_get(rc->pcpu);
				if (mtx_trylock(&pcpu->mtx))
				ro = &pcpu->ro;

				return ro;
				zleiAuthorUnsubmitted Done Inline Actions These per AF method indeed can be turned into internal then consumers will use unified APIs listed above. zlei: These per AF method indeed can be turned into internal then consumers will use unified APIs…
				}

				static inline void
				route_cache_release(struct route *ro)
				{
				struct route_cache_pcpu *pcpu;

				if (ro != NULL) {
				pcpu = __containerof(ro, struct route_cache_pcpu, ro);
				mtx_assert(&pcpu->mtx, MA_OWNED);
				mtx_unlock(&pcpu->mtx);
				}
				zleiAuthorUnsubmitted Done Inline Actions This is important as if the lock of PCPU route cache is held by other thread, then we never block and fallback to no route caching. zlei: This is important as if the lock of PCPU route cache is held by other thread, then we never…
				}

				#ifdef INET6
				static inline struct route_in6 *
				route_cache_acquire6(struct route_cache *rc)
				{
				struct route_cache_pcpu *pcpu;
				struct route_in6 *ro = NULL;

				pcpu = zpcpu_get(rc->pcpu);
				if (mtx_trylock(&pcpu->mtx))
				ro = &pcpu->ro6;

				return ro;
				}

				static inline void
				route_cache_release6(struct route_in6 *ro)
				{
				struct route_cache_pcpu *pcpu;

				if (ro != NULL) {
				pcpu = __containerof(ro, struct route_cache_pcpu, ro6);
				mtx_assert(&pcpu->mtx, MA_OWNED);
				mtx_unlock(&pcpu->mtx);
				}
				}
				#endif

				#endif