1 /*
2 * GPL HEADER START
3 *
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
9
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License version 2 for more details. A copy is
14 * included in the COPYING file that accompanied this code.
15
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 *
20 * GPL HEADER END
21 */
22 /*
23 * Copyright (c) 2011 Intel Corporation
24 *
25 * Copyright 2012 Xyratex Technology Limited
26 */
27 /*
28 * lustre/ptlrpc/nrs_fifo.c
29 *
30 * Network Request Scheduler (NRS) FIFO policy
31 *
32 * Handles RPCs in a FIFO manner, as received from the network. This policy is
33 * a logical wrapper around previous, non-NRS functionality. It is used as the
34 * default and fallback policy for all types of RPCs on all PTLRPC service
35 * partitions, for both regular and high-priority NRS heads. Default here means
36 * the policy is the one enabled at PTLRPC service partition startup time, and
37 * fallback means the policy is used to handle RPCs that are not handled
38 * successfully or are not handled at all by any primary policy that may be
39 * enabled on a given NRS head.
40 *
41 * Author: Liang Zhen <liang@whamcloud.com>
42 * Author: Nikitas Angelinas <nikitas_angelinas@xyratex.com>
43 */
44 /**
45 * \addtogoup nrs
46 * @{
47 */
48
49 #define DEBUG_SUBSYSTEM S_RPC
50 #include "../include/obd_support.h"
51 #include "../include/obd_class.h"
52 #include "../../include/linux/libcfs/libcfs.h"
53 #include "ptlrpc_internal.h"
54
55 /**
56 * \name fifo
57 *
58 * The FIFO policy is a logical wrapper around previous, non-NRS functionality.
59 * It schedules RPCs in the same order as they are queued from LNet.
60 *
61 * @{
62 */
63
64 #define NRS_POL_NAME_FIFO "fifo"
65
66 /**
67 * Is called before the policy transitions into
68 * ptlrpc_nrs_pol_state::NRS_POL_STATE_STARTED; allocates and initializes a
69 * policy-specific private data structure.
70 *
71 * \param[in] policy The policy to start
72 *
73 * \retval -ENOMEM OOM error
74 * \retval 0 success
75 *
76 * \see nrs_policy_register()
77 * \see nrs_policy_ctl()
78 */
nrs_fifo_start(struct ptlrpc_nrs_policy * policy)79 static int nrs_fifo_start(struct ptlrpc_nrs_policy *policy)
80 {
81 struct nrs_fifo_head *head;
82
83 head = kzalloc_node(sizeof(*head), GFP_NOFS,
84 cfs_cpt_spread_node(nrs_pol2cptab(policy),
85 nrs_pol2cptid(policy)));
86 if (head == NULL)
87 return -ENOMEM;
88
89 INIT_LIST_HEAD(&head->fh_list);
90 policy->pol_private = head;
91 return 0;
92 }
93
94 /**
95 * Is called before the policy transitions into
96 * ptlrpc_nrs_pol_state::NRS_POL_STATE_STOPPED; deallocates the policy-specific
97 * private data structure.
98 *
99 * \param[in] policy The policy to stop
100 *
101 * \see nrs_policy_stop0()
102 */
nrs_fifo_stop(struct ptlrpc_nrs_policy * policy)103 static void nrs_fifo_stop(struct ptlrpc_nrs_policy *policy)
104 {
105 struct nrs_fifo_head *head = policy->pol_private;
106
107 LASSERT(head != NULL);
108 LASSERT(list_empty(&head->fh_list));
109
110 kfree(head);
111 }
112
113 /**
114 * Is called for obtaining a FIFO policy resource.
115 *
116 * \param[in] policy The policy on which the request is being asked for
117 * \param[in] nrq The request for which resources are being taken
118 * \param[in] parent Parent resource, unused in this policy
119 * \param[out] resp Resources references are placed in this array
120 * \param[in] moving_req Signifies limited caller context; unused in this
121 * policy
122 *
123 * \retval 1 The FIFO policy only has a one-level resource hierarchy, as since
124 * it implements a simple scheduling algorithm in which request
125 * priority is determined on the request arrival order, it does not
126 * need to maintain a set of resources that would otherwise be used
127 * to calculate a request's priority.
128 *
129 * \see nrs_resource_get_safe()
130 */
nrs_fifo_res_get(struct ptlrpc_nrs_policy * policy,struct ptlrpc_nrs_request * nrq,const struct ptlrpc_nrs_resource * parent,struct ptlrpc_nrs_resource ** resp,bool moving_req)131 static int nrs_fifo_res_get(struct ptlrpc_nrs_policy *policy,
132 struct ptlrpc_nrs_request *nrq,
133 const struct ptlrpc_nrs_resource *parent,
134 struct ptlrpc_nrs_resource **resp, bool moving_req)
135 {
136 /**
137 * Just return the resource embedded inside nrs_fifo_head, and end this
138 * resource hierarchy reference request.
139 */
140 *resp = &((struct nrs_fifo_head *)policy->pol_private)->fh_res;
141 return 1;
142 }
143
144 /**
145 * Called when getting a request from the FIFO policy for handling, or just
146 * peeking; removes the request from the policy when it is to be handled.
147 *
148 * \param[in] policy The policy
149 * \param[in] peek When set, signifies that we just want to examine the
150 * request, and not handle it, so the request is not removed
151 * from the policy.
152 * \param[in] force Force the policy to return a request; unused in this
153 * policy
154 *
155 * \retval The request to be handled; this is the next request in the FIFO
156 * queue
157 *
158 * \see ptlrpc_nrs_req_get_nolock()
159 * \see nrs_request_get()
160 */
161 static
nrs_fifo_req_get(struct ptlrpc_nrs_policy * policy,bool peek,bool force)162 struct ptlrpc_nrs_request *nrs_fifo_req_get(struct ptlrpc_nrs_policy *policy,
163 bool peek, bool force)
164 {
165 struct nrs_fifo_head *head = policy->pol_private;
166 struct ptlrpc_nrs_request *nrq;
167
168 nrq = unlikely(list_empty(&head->fh_list)) ? NULL :
169 list_entry(head->fh_list.next, struct ptlrpc_nrs_request,
170 nr_u.fifo.fr_list);
171
172 if (likely(!peek && nrq != NULL)) {
173 struct ptlrpc_request *req = container_of(nrq,
174 struct ptlrpc_request,
175 rq_nrq);
176
177 list_del_init(&nrq->nr_u.fifo.fr_list);
178
179 CDEBUG(D_RPCTRACE, "NRS start %s request from %s, seq: %llu\n",
180 policy->pol_desc->pd_name, libcfs_id2str(req->rq_peer),
181 nrq->nr_u.fifo.fr_sequence);
182 }
183
184 return nrq;
185 }
186
187 /**
188 * Adds request \a nrq to \a policy's list of queued requests
189 *
190 * \param[in] policy The policy
191 * \param[in] nrq The request to add
192 *
193 * \retval 0 success; nrs_request_enqueue() assumes this function will always
194 * succeed
195 */
nrs_fifo_req_add(struct ptlrpc_nrs_policy * policy,struct ptlrpc_nrs_request * nrq)196 static int nrs_fifo_req_add(struct ptlrpc_nrs_policy *policy,
197 struct ptlrpc_nrs_request *nrq)
198 {
199 struct nrs_fifo_head *head;
200
201 head = container_of(nrs_request_resource(nrq), struct nrs_fifo_head,
202 fh_res);
203 /**
204 * Only used for debugging
205 */
206 nrq->nr_u.fifo.fr_sequence = head->fh_sequence++;
207 list_add_tail(&nrq->nr_u.fifo.fr_list, &head->fh_list);
208
209 return 0;
210 }
211
212 /**
213 * Removes request \a nrq from \a policy's list of queued requests.
214 *
215 * \param[in] policy The policy
216 * \param[in] nrq The request to remove
217 */
nrs_fifo_req_del(struct ptlrpc_nrs_policy * policy,struct ptlrpc_nrs_request * nrq)218 static void nrs_fifo_req_del(struct ptlrpc_nrs_policy *policy,
219 struct ptlrpc_nrs_request *nrq)
220 {
221 LASSERT(!list_empty(&nrq->nr_u.fifo.fr_list));
222 list_del_init(&nrq->nr_u.fifo.fr_list);
223 }
224
225 /**
226 * Prints a debug statement right before the request \a nrq stops being
227 * handled.
228 *
229 * \param[in] policy The policy handling the request
230 * \param[in] nrq The request being handled
231 *
232 * \see ptlrpc_server_finish_request()
233 * \see ptlrpc_nrs_req_stop_nolock()
234 */
nrs_fifo_req_stop(struct ptlrpc_nrs_policy * policy,struct ptlrpc_nrs_request * nrq)235 static void nrs_fifo_req_stop(struct ptlrpc_nrs_policy *policy,
236 struct ptlrpc_nrs_request *nrq)
237 {
238 struct ptlrpc_request *req = container_of(nrq, struct ptlrpc_request,
239 rq_nrq);
240
241 CDEBUG(D_RPCTRACE, "NRS stop %s request from %s, seq: %llu\n",
242 policy->pol_desc->pd_name, libcfs_id2str(req->rq_peer),
243 nrq->nr_u.fifo.fr_sequence);
244 }
245
246 /**
247 * FIFO policy operations
248 */
249 static const struct ptlrpc_nrs_pol_ops nrs_fifo_ops = {
250 .op_policy_start = nrs_fifo_start,
251 .op_policy_stop = nrs_fifo_stop,
252 .op_res_get = nrs_fifo_res_get,
253 .op_req_get = nrs_fifo_req_get,
254 .op_req_enqueue = nrs_fifo_req_add,
255 .op_req_dequeue = nrs_fifo_req_del,
256 .op_req_stop = nrs_fifo_req_stop,
257 };
258
259 /**
260 * FIFO policy configuration
261 */
262 struct ptlrpc_nrs_pol_conf nrs_conf_fifo = {
263 .nc_name = NRS_POL_NAME_FIFO,
264 .nc_ops = &nrs_fifo_ops,
265 .nc_compat = nrs_policy_compat_all,
266 .nc_flags = PTLRPC_NRS_FL_FALLBACK |
267 PTLRPC_NRS_FL_REG_START
268 };
269
270 /** @} fifo */
271
272 /** @} nrs */
273