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Neither the name of Novell Inc. nor the names of its contributors 60 * may be used to endorse or promote products derived from this 61 * this software without specific prior written permission. 62 * 63 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY 64 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 65 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 66 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY 67 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 68 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 69 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 70 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 71 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 72 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 73 * 74 * @APPLE_LICENSE_HEADER_END@ 75 */ 76 77/* 78** 79** NAME: 80** 81** dgpkt.h 82** 83** FACILITY: 84** 85** Remote Procedure Call (RPC) 86** 87** ABSTRACT: 88** 89** Routines for managing the datagram packet pool. 90** 91** 92*/ 93 94#ifndef _DGPKT_H 95#define _DGPKT_H 96 97/* ========================================================================= */ 98/* 99 * Datagram Packet Rationing 100 * 101 * Every active call requires a packet pool "reservation". The purpose 102 * of this reservation is to guarantee that the call can always make 103 * progress. 104 * 105 * "Progress" is defined as the ability to exchange at least one packet 106 * at a time over a conversation. 107 * 108 * "Rationing" is the condition where calls are only allowed to use 109 * their reserved packet. 110 * 111 * The condition that invokes rationing is: the number of available 112 * packets in the free pool is less than or equal to the number of 113 * packet reservations. 114 */ 115 116/* 117 * Define the maximum number of packet's (used for both xqe's and rqe's) 118 * that we'll ever allocate. 119 */ 120 121#ifndef RPC_C_DG_PKT_MAX 122#define RPC_C_DG_PKT_MAX 100000 123#endif 124 125/* 126 * Define the number of packets that should be allocated during 127 * initialization to seed the free list. 128 */ 129 130#ifndef RPC_C_DG_PKT_INIT_CNT 131#define RPC_C_DG_PKT_INIT_CNT 48 132#endif 133 134/* 135 * One of the conditions on which the packet rationing scheme is based is 136 * that, when rationing is necessary, all RPC threads will be able to drain 137 * their queues and use only the packets they have reserved. One possible 138 * scenario is which this wouldn't be the case is if in a group of N 139 * inter-communicating processes (where N can be 1, in the case of KRPC) 140 * all packets got queued up by clients before the rationing state was 141 * entered. In such a case, there would be no reservations to grant to 142 * the server sides of the calls, and thus no way for the clients to drain. 143 * 144 * Avoiding this potential deadlock requires that we guarantee that at least 145 * one server call can be started for such a group of N processes. Since N can 146 * be 1, it follows that every process must be guaranteed that it can always 147 * start at least one server call. 148 * 149 * We guarantee the capability of running server calls by setting aside 150 * reservations for that purpose at startup. A single reservation would be 151 * sufficient to guarantee the correctness of the algorithm, but making a few 152 * reservations will increase the fairness in the worst of cases. 153 */ 154#ifndef RPC_C_DG_PKT_INIT_SERVER_RESVS 155#define RPC_C_DG_PKT_INIT_SERVER_RESVS 5 156#endif 157 158/* 159 * The following structure is used to build the free packet pool. Since 160 * the pool contains both xqe's and rqe's, we need a third, neutral pointer 161 * which can be used to access either type of transmission element. 162 */ 163 164typedef struct rpc_dg_pkt_pool_elt_t { 165 union { 166 struct rpc_dg_pkt_pool_elt_t *next; /* for building a free list */ 167 struct { 168 rpc_dg_xmitq_elt_t xqe; 169 rpc_dg_pkt_body_t pkt; 170 } xqe; /* for handling xqe's */ 171 struct { 172 rpc_dg_recvq_elt_t rqe; 173 rpc_dg_raw_pkt_t pkt; 174 unsigned32 pad1; /* Need some padding to get */ 175 unsigned32 pad2; /* 0 MOD 8 byte alignment */ 176 rpc_dg_sock_pool_elt_p_t sock_ref; 177 } rqe; /* for handling rqe's */ 178 } u; 179 boolean is_on_free_list; 180} rpc_dg_pkt_pool_elt_t, *rpc_dg_pkt_pool_elt_p_t; 181 182/* 183 * The packet pool is a global structure which contains: 184 * - a mutex to lock when modifying this structure 185 * - the max # of packets that can be allocated 186 * - a counter of the number of packets remaining to be allocated 187 * - number of packet reservations currently held 188 * - counters of the number of currently active xqe's/rqe's 189 * and failed rqe allocations (this should always be 0 if things 190 * are working) and xqe allocation attempts that had to block. 191 * - a counter of the number of packets on the free list 192 * - a linked list of free packets 193 * - a pointer to the tail of the free list 194 * - pointers to the head and tail of a linked list of call 195 * handles that are waiting to be signalled when a packet 196 * becomes available. 197 * - pointers to the head and tail of a linked list of call 198 * handles that are waiting to be signalled when a packet 199 * reservation becomes available. 200 */ 201 202typedef struct rpc_dg_pkt_pool_t { 203 rpc_mutex_t pkt_mutex; 204 unsigned32 max_pkt_count; 205 unsigned32 pkt_count; 206 unsigned32 reservations; 207 unsigned32 srv_resv_avail; 208 unsigned32 max_resv_pkt; /* # of pkts for the largest fragment */ 209 unsigned32 active_rqes; 210 unsigned32 active_xqes; 211 unsigned32 failed_alloc_rqe; 212 unsigned32 blocked_alloc_xqe; 213 unsigned32 free_count; 214 unsigned is_rationing: 1; /* T => is rationing */ 215 unsigned low_on_pkts: 1; /* T => pkt pool is low */ 216 rpc_dg_pkt_pool_elt_p_t free_list; 217 rpc_dg_pkt_pool_elt_p_t free_list_tail; 218 rpc_dg_call_p_t pkt_waiters_head, pkt_waiters_tail; 219 rpc_dg_call_p_t rsv_waiters_head, rsv_waiters_tail; 220} rpc_dg_pkt_pool_t; 221 222EXTERNAL rpc_dg_pkt_pool_t rpc_g_dg_pkt_pool; 223 224/* 225 * Macros for locking/unlocking the packet pool's mutex. 226 */ 227 228#define RPC_DG_PKT_POOL_LOCK(junk) RPC_MUTEX_LOCK(rpc_g_dg_pkt_pool.pkt_mutex) 229#define RPC_DG_PKT_POOL_UNLOCK(junk) RPC_MUTEX_UNLOCK(rpc_g_dg_pkt_pool.pkt_mutex) 230#define RPC_DG_PKT_POOL_LOCK_ASSERT(junk) \ 231 RPC_MUTEX_LOCK_ASSERT(rpc_g_dg_pkt_pool.pkt_mutex) 232 233/* 234 * Macro to determine if we are in the packet rationing state. 235 * 236 * This macro requires that the packet pool is locked. 237 */ 238 239#define RPC_DG_PKT_RATIONING(junk) \ 240 (rpc_g_dg_pkt_pool.free_count + rpc_g_dg_pkt_pool.pkt_count <= \ 241 rpc_g_dg_pkt_pool.reservations) 242 243/* ========================================================================= */ 244 245PRIVATE void rpc__dg_pkt_pool_init (void); 246 247PRIVATE void rpc__dg_pkt_pool_fork_handler ( 248 rpc_fork_stage_id_t /*stage*/ 249 ); 250 251PRIVATE rpc_dg_xmitq_elt_p_t rpc__dg_pkt_alloc_xqe ( 252 rpc_dg_call_p_t /*call*/, 253 unsigned32 * /*st*/ 254 ); 255 256PRIVATE rpc_dg_recvq_elt_p_t rpc__dg_pkt_alloc_rqe ( 257 rpc_dg_ccall_p_t /*ccall*/ 258 ); 259 260PRIVATE void rpc__dg_pkt_free_xqe ( 261 rpc_dg_xmitq_elt_p_t /*pkt*/, 262 rpc_dg_call_p_t /*call*/ 263 ); 264 265PRIVATE void rpc__dg_pkt_free_rqe_for_stub ( 266 rpc_dg_recvq_elt_p_t /*pkt*/ 267 ); 268 269PRIVATE void rpc__dg_pkt_free_rqe ( 270 rpc_dg_recvq_elt_p_t /*pkt*/, 271 rpc_dg_call_p_t /*call*/ 272 ); 273 274PRIVATE boolean32 rpc__dg_pkt_adjust_reservation ( 275 rpc_dg_call_p_t /*call*/, 276 unsigned32 /*nreq*/, 277 boolean32 /*block*/ 278 ); 279 280PRIVATE void rpc__dg_pkt_cancel_reservation ( 281 rpc_dg_call_p_t /*call*/ 282 ); 283 284PRIVATE boolean32 rpc__dg_pkt_is_rationing ( 285 boolean32 * /*low_on_pkts*/ 286 ); 287#endif /* _DGPKT_H */ 288