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7 * it under the terms of the GNU General Public License version 2 only,
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12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 * included in the COPYING file that accompanied this code.
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18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 * Copyright (c) 2011 Intel Corporation
25 * Copyright 2012 Xyratex Technology Limited
28 * lustre/ptlrpc/nrs_fifo.c
30 * Network Request Scheduler (NRS) FIFO policy
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.
41 * Author: Liang Zhen <liang@whamcloud.com>
42 * Author: Nikitas Angelinas <nikitas_angelinas@xyratex.com>
49 #define DEBUG_SUBSYSTEM S_RPC
51 #include <liblustre.h>
53 #include <obd_support.h>
54 #include <obd_class.h>
55 #include <libcfs/libcfs.h>
56 #include "ptlrpc_internal.h"
61 * The FIFO policy is a logical wrapper around previous, non-NRS functionality.
62 * It schedules RPCs in the same order as they are queued from LNet.
67 #define NRS_POL_NAME_FIFO "fifo"
70 * Is called before the policy transitions into
71 * ptlrpc_nrs_pol_state::NRS_POL_STATE_STARTED; allocates and initializes a
72 * policy-specific private data structure.
74 * \param[in] policy The policy to start
76 * \retval -ENOMEM OOM error
79 * \see nrs_policy_register()
80 * \see nrs_policy_ctl()
82 static int nrs_fifo_start(struct ptlrpc_nrs_policy *policy)
84 struct nrs_fifo_head *head;
86 OBD_CPT_ALLOC_PTR(head, nrs_pol2cptab(policy), nrs_pol2cptid(policy));
90 CFS_INIT_LIST_HEAD(&head->fh_list);
91 policy->pol_private = head;
96 * Is called before the policy transitions into
97 * ptlrpc_nrs_pol_state::NRS_POL_STATE_STOPPED; deallocates the policy-specific
98 * private data structure.
100 * \param[in] policy The policy to stop
102 * \see nrs_policy_stop0()
104 static void nrs_fifo_stop(struct ptlrpc_nrs_policy *policy)
106 struct nrs_fifo_head *head = policy->pol_private;
108 LASSERT(head != NULL);
109 LASSERT(cfs_list_empty(&head->fh_list));
115 * Is called for obtaining a FIFO policy resource.
117 * \param[in] policy The policy on which the request is being asked for
118 * \param[in] nrq The request for which resources are being taken
119 * \param[in] parent Parent resource, unused in this policy
120 * \param[out] resp Resources references are placed in this array
121 * \param[in] moving_req Signifies limited caller context; unused in this
124 * \retval 1 The FIFO policy only has a one-level resource hierarchy, as since
125 * it implements a simple scheduling algorithm in which request
126 * priority is determined on the request arrival order, it does not
127 * need to maintain a set of resources that would otherwise be used
128 * to calculate a request's priority.
130 * \see nrs_resource_get_safe()
132 static int nrs_fifo_res_get(struct ptlrpc_nrs_policy *policy,
133 struct ptlrpc_nrs_request *nrq,
134 const struct ptlrpc_nrs_resource *parent,
135 struct ptlrpc_nrs_resource **resp, bool moving_req)
138 * Just return the resource embedded inside nrs_fifo_head, and end this
139 * resource hierarchy reference request.
141 *resp = &((struct nrs_fifo_head *)policy->pol_private)->fh_res;
146 * Called when getting a request from the FIFO policy for handling, or just
147 * peeking; removes the request from the policy when it is to be handled.
149 * \param[in] policy The policy
150 * \param[in] peek When set, signifies that we just want to examine the
151 * request, and not handle it, so the request is not removed
153 * \param[in] force Force the policy to return a request; unused in this
156 * \retval The request to be handled; this is the next request in the FIFO
159 * \see ptlrpc_nrs_req_get_nolock()
160 * \see nrs_request_get()
163 struct ptlrpc_nrs_request * nrs_fifo_req_get(struct ptlrpc_nrs_policy *policy,
164 bool peek, bool force)
166 struct nrs_fifo_head *head = policy->pol_private;
167 struct ptlrpc_nrs_request *nrq;
169 nrq = unlikely(cfs_list_empty(&head->fh_list)) ? NULL :
170 cfs_list_entry(head->fh_list.next, struct ptlrpc_nrs_request,
173 if (likely(!peek && nrq != NULL)) {
174 struct ptlrpc_request *req = container_of(nrq,
175 struct ptlrpc_request,
178 cfs_list_del_init(&nrq->nr_u.fifo.fr_list);
180 CDEBUG(D_RPCTRACE, "NRS start %s request from %s, seq: "LPU64
181 "\n", policy->pol_desc->pd_name,
182 libcfs_id2str(req->rq_peer), nrq->nr_u.fifo.fr_sequence);
189 * Adds request \a nrq to \a policy's list of queued requests
191 * \param[in] policy The policy
192 * \param[in] nrq The request to add
194 * \retval 0 success; nrs_request_enqueue() assumes this function will always
197 static int nrs_fifo_req_add(struct ptlrpc_nrs_policy *policy,
198 struct ptlrpc_nrs_request *nrq)
200 struct nrs_fifo_head *head;
202 head = container_of(nrs_request_resource(nrq), struct nrs_fifo_head,
205 * Only used for debugging
207 nrq->nr_u.fifo.fr_sequence = head->fh_sequence++;
208 cfs_list_add_tail(&nrq->nr_u.fifo.fr_list, &head->fh_list);
214 * Removes request \a nrq from \a policy's list of queued requests.
216 * \param[in] policy The policy
217 * \param[in] nrq The request to remove
219 static void nrs_fifo_req_del(struct ptlrpc_nrs_policy *policy,
220 struct ptlrpc_nrs_request *nrq)
222 LASSERT(!cfs_list_empty(&nrq->nr_u.fifo.fr_list));
223 cfs_list_del_init(&nrq->nr_u.fifo.fr_list);
227 * Prints a debug statement right before the request \a nrq stops being
230 * \param[in] policy The policy handling the request
231 * \param[in] nrq The request being handled
233 * \see ptlrpc_server_finish_request()
234 * \see ptlrpc_nrs_req_stop_nolock()
236 static void nrs_fifo_req_stop(struct ptlrpc_nrs_policy *policy,
237 struct ptlrpc_nrs_request *nrq)
239 struct ptlrpc_request *req = container_of(nrq, struct ptlrpc_request,
242 CDEBUG(D_RPCTRACE, "NRS stop %s request from %s, seq: "LPU64"\n",
243 policy->pol_desc->pd_name, libcfs_id2str(req->rq_peer),
244 nrq->nr_u.fifo.fr_sequence);
248 * FIFO policy operations
250 static const struct ptlrpc_nrs_pol_ops nrs_fifo_ops = {
251 .op_policy_start = nrs_fifo_start,
252 .op_policy_stop = nrs_fifo_stop,
253 .op_res_get = nrs_fifo_res_get,
254 .op_req_get = nrs_fifo_req_get,
255 .op_req_enqueue = nrs_fifo_req_add,
256 .op_req_dequeue = nrs_fifo_req_del,
257 .op_req_stop = nrs_fifo_req_stop,
261 * FIFO policy configuration
263 struct ptlrpc_nrs_pol_conf nrs_conf_fifo = {
264 .nc_name = NRS_POL_NAME_FIFO,
265 .nc_ops = &nrs_fifo_ops,
266 .nc_compat = nrs_policy_compat_all,
267 .nc_flags = PTLRPC_NRS_FL_FALLBACK |
268 PTLRPC_NRS_FL_REG_START