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Diffstat (limited to 'drivers/staging/lustre/lustre/include/lustre_nrs.h')
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1 files changed, 717 insertions, 0 deletions
diff --git a/drivers/staging/lustre/lustre/include/lustre_nrs.h b/drivers/staging/lustre/lustre/include/lustre_nrs.h new file mode 100644 index 000000000000..a5028aaa19cd --- /dev/null +++ b/drivers/staging/lustre/lustre/include/lustre_nrs.h @@ -0,0 +1,717 @@ +/* + * GPL HEADER START + * + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 only, + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License version 2 for more details. + * + * You should have received a copy of the GNU General Public License + * version 2 along with this program; If not, see + * http://www.gnu.org/licenses/gpl-2.0.html + * + * GPL HEADER END + */ +/* + * Copyright (c) 2014, Intel Corporation. + * + * Copyright 2012 Xyratex Technology Limited + */ +/* + * + * Network Request Scheduler (NRS) + * + */ + +#ifndef _LUSTRE_NRS_H +#define _LUSTRE_NRS_H + +/** + * \defgroup nrs Network Request Scheduler + * @{ + */ +struct ptlrpc_nrs_policy; +struct ptlrpc_nrs_resource; +struct ptlrpc_nrs_request; + +/** + * NRS control operations. + * + * These are common for all policies. + */ +enum ptlrpc_nrs_ctl { + /** + * Not a valid opcode. + */ + PTLRPC_NRS_CTL_INVALID, + /** + * Activate the policy. + */ + PTLRPC_NRS_CTL_START, + /** + * Reserved for multiple primary policies, which may be a possibility + * in the future. + */ + PTLRPC_NRS_CTL_STOP, + /** + * Policies can start using opcodes from this value and onwards for + * their own purposes; the assigned value itself is arbitrary. + */ + PTLRPC_NRS_CTL_1ST_POL_SPEC = 0x20, +}; + +/** + * NRS policy operations. + * + * These determine the behaviour of a policy, and are called in response to + * NRS core events. + */ +struct ptlrpc_nrs_pol_ops { + /** + * Called during policy registration; this operation is optional. + * + * \param[in,out] policy The policy being initialized + */ + int (*op_policy_init)(struct ptlrpc_nrs_policy *policy); + /** + * Called during policy unregistration; this operation is optional. + * + * \param[in,out] policy The policy being unregistered/finalized + */ + void (*op_policy_fini)(struct ptlrpc_nrs_policy *policy); + /** + * Called when activating a policy via lprocfs; policies allocate and + * initialize their resources here; this operation is optional. + * + * \param[in,out] policy The policy being started + * + * \see nrs_policy_start_locked() + */ + int (*op_policy_start)(struct ptlrpc_nrs_policy *policy); + /** + * Called when deactivating a policy via lprocfs; policies deallocate + * their resources here; this operation is optional + * + * \param[in,out] policy The policy being stopped + * + * \see nrs_policy_stop0() + */ + void (*op_policy_stop)(struct ptlrpc_nrs_policy *policy); + /** + * Used for policy-specific operations; i.e. not generic ones like + * \e PTLRPC_NRS_CTL_START and \e PTLRPC_NRS_CTL_GET_INFO; analogous + * to an ioctl; this operation is optional. + * + * \param[in,out] policy The policy carrying out operation \a opc + * \param[in] opc The command operation being carried out + * \param[in,out] arg An generic buffer for communication between the + * user and the control operation + * + * \retval -ve error + * \retval 0 success + * + * \see ptlrpc_nrs_policy_control() + */ + int (*op_policy_ctl)(struct ptlrpc_nrs_policy *policy, + enum ptlrpc_nrs_ctl opc, void *arg); + + /** + * Called when obtaining references to the resources of the resource + * hierarchy for a request that has arrived for handling at the PTLRPC + * service. Policies should return -ve for requests they do not wish + * to handle. This operation is mandatory. + * + * \param[in,out] policy The policy we're getting resources for. + * \param[in,out] nrq The request we are getting resources for. + * \param[in] parent The parent resource of the resource being + * requested; set to NULL if none. + * \param[out] resp The resource is to be returned here; the + * fallback policy in an NRS head should + * \e always return a non-NULL pointer value. + * \param[in] moving_req When set, signifies that this is an attempt + * to obtain resources for a request being moved + * to the high-priority NRS head by + * ldlm_lock_reorder_req(). + * This implies two things: + * 1. We are under obd_export::exp_rpc_lock and + * so should not sleep. + * 2. We should not perform non-idempotent or can + * skip performing idempotent operations that + * were carried out when resources were first + * taken for the request when it was initialized + * in ptlrpc_nrs_req_initialize(). + * + * \retval 0, +ve The level of the returned resource in the resource + * hierarchy; currently only 0 (for a non-leaf resource) + * and 1 (for a leaf resource) are supported by the + * framework. + * \retval -ve error + * + * \see ptlrpc_nrs_req_initialize() + * \see ptlrpc_nrs_hpreq_add_nolock() + * \see ptlrpc_nrs_req_hp_move() + */ + int (*op_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); + /** + * Called when releasing references taken for resources in the resource + * hierarchy for the request; this operation is optional. + * + * \param[in,out] policy The policy the resource belongs to + * \param[in] res The resource to be freed + * + * \see ptlrpc_nrs_req_finalize() + * \see ptlrpc_nrs_hpreq_add_nolock() + * \see ptlrpc_nrs_req_hp_move() + */ + void (*op_res_put)(struct ptlrpc_nrs_policy *policy, + const struct ptlrpc_nrs_resource *res); + + /** + * Obtains a request for handling from the policy, and optionally + * removes the request from the policy; this operation is mandatory. + * + * \param[in,out] policy The policy to poll + * \param[in] peek When set, signifies that we just want to + * examine the request, and not handle it, so the + * request is not removed from the policy. + * \param[in] force When set, it will force a policy to return a + * request if it has one queued. + * + * \retval NULL No request available for handling + * \retval valid-pointer The request polled for handling + * + * \see ptlrpc_nrs_req_get_nolock() + */ + struct ptlrpc_nrs_request * + (*op_req_get)(struct ptlrpc_nrs_policy *policy, bool peek, + bool force); + /** + * Called when attempting to add a request to a policy for later + * handling; this operation is mandatory. + * + * \param[in,out] policy The policy on which to enqueue \a nrq + * \param[in,out] nrq The request to enqueue + * + * \retval 0 success + * \retval != 0 error + * + * \see ptlrpc_nrs_req_add_nolock() + */ + int (*op_req_enqueue)(struct ptlrpc_nrs_policy *policy, + struct ptlrpc_nrs_request *nrq); + /** + * Removes a request from the policy's set of pending requests. Normally + * called after a request has been polled successfully from the policy + * for handling; this operation is mandatory. + * + * \param[in,out] policy The policy the request \a nrq belongs to + * \param[in,out] nrq The request to dequeue + * + * \see ptlrpc_nrs_req_del_nolock() + */ + void (*op_req_dequeue)(struct ptlrpc_nrs_policy *policy, + struct ptlrpc_nrs_request *nrq); + /** + * Called after the request being carried out. Could be used for + * job/resource control; this operation is optional. + * + * \param[in,out] policy The policy which is stopping to handle request + * \a nrq + * \param[in,out] nrq The request + * + * \pre assert_spin_locked(&svcpt->scp_req_lock) + * + * \see ptlrpc_nrs_req_stop_nolock() + */ + void (*op_req_stop)(struct ptlrpc_nrs_policy *policy, + struct ptlrpc_nrs_request *nrq); + /** + * Registers the policy's lprocfs interface with a PTLRPC service. + * + * \param[in] svc The service + * + * \retval 0 success + * \retval != 0 error + */ + int (*op_lprocfs_init)(struct ptlrpc_service *svc); + /** + * Unegisters the policy's lprocfs interface with a PTLRPC service. + * + * In cases of failed policy registration in + * \e ptlrpc_nrs_policy_register(), this function may be called for a + * service which has not registered the policy successfully, so + * implementations of this method should make sure their operations are + * safe in such cases. + * + * \param[in] svc The service + */ + void (*op_lprocfs_fini)(struct ptlrpc_service *svc); +}; + +/** + * Policy flags + */ +enum nrs_policy_flags { + /** + * Fallback policy, use this flag only on a single supported policy per + * service. The flag cannot be used on policies that use + * \e PTLRPC_NRS_FL_REG_EXTERN + */ + PTLRPC_NRS_FL_FALLBACK = BIT(0), + /** + * Start policy immediately after registering. + */ + PTLRPC_NRS_FL_REG_START = BIT(1), + /** + * This is a policy registering from a module different to the one NRS + * core ships in (currently ptlrpc). + */ + PTLRPC_NRS_FL_REG_EXTERN = BIT(2), +}; + +/** + * NRS queue type. + * + * Denotes whether an NRS instance is for handling normal or high-priority + * RPCs, or whether an operation pertains to one or both of the NRS instances + * in a service. + */ +enum ptlrpc_nrs_queue_type { + PTLRPC_NRS_QUEUE_REG = BIT(0), + PTLRPC_NRS_QUEUE_HP = BIT(1), + PTLRPC_NRS_QUEUE_BOTH = (PTLRPC_NRS_QUEUE_REG | PTLRPC_NRS_QUEUE_HP) +}; + +/** + * NRS head + * + * A PTLRPC service has at least one NRS head instance for handling normal + * priority RPCs, and may optionally have a second NRS head instance for + * handling high-priority RPCs. Each NRS head maintains a list of available + * policies, of which one and only one policy is acting as the fallback policy, + * and optionally a different policy may be acting as the primary policy. For + * all RPCs handled by this NRS head instance, NRS core will first attempt to + * enqueue the RPC using the primary policy (if any). The fallback policy is + * used in the following cases: + * - when there was no primary policy in the + * ptlrpc_nrs_pol_state::NRS_POL_STATE_STARTED state at the time the request + * was initialized. + * - when the primary policy that was at the + * ptlrpc_nrs_pol_state::PTLRPC_NRS_POL_STATE_STARTED state at the time the + * RPC was initialized, denoted it did not wish, or for some other reason was + * not able to handle the request, by returning a non-valid NRS resource + * reference. + * - when the primary policy that was at the + * ptlrpc_nrs_pol_state::PTLRPC_NRS_POL_STATE_STARTED state at the time the + * RPC was initialized, fails later during the request enqueueing stage. + * + * \see nrs_resource_get_safe() + * \see nrs_request_enqueue() + */ +struct ptlrpc_nrs { + spinlock_t nrs_lock; + /** XXX Possibly replace svcpt->scp_req_lock with another lock here. */ + /** + * List of registered policies + */ + struct list_head nrs_policy_list; + /** + * List of policies with queued requests. Policies that have any + * outstanding requests are queued here, and this list is queried + * in a round-robin manner from NRS core when obtaining a request + * for handling. This ensures that requests from policies that at some + * point transition away from the + * ptlrpc_nrs_pol_state::NRS_POL_STATE_STARTED state are drained. + */ + struct list_head nrs_policy_queued; + /** + * Service partition for this NRS head + */ + struct ptlrpc_service_part *nrs_svcpt; + /** + * Primary policy, which is the preferred policy for handling RPCs + */ + struct ptlrpc_nrs_policy *nrs_policy_primary; + /** + * Fallback policy, which is the backup policy for handling RPCs + */ + struct ptlrpc_nrs_policy *nrs_policy_fallback; + /** + * This NRS head handles either HP or regular requests + */ + enum ptlrpc_nrs_queue_type nrs_queue_type; + /** + * # queued requests from all policies in this NRS head + */ + unsigned long nrs_req_queued; + /** + * # scheduled requests from all policies in this NRS head + */ + unsigned long nrs_req_started; + /** + * # policies on this NRS + */ + unsigned int nrs_num_pols; + /** + * This NRS head is in progress of starting a policy + */ + unsigned int nrs_policy_starting:1; + /** + * In progress of shutting down the whole NRS head; used during + * unregistration + */ + unsigned int nrs_stopping:1; + /** + * NRS policy is throttling request + */ + unsigned int nrs_throttling:1; +}; + +#define NRS_POL_NAME_MAX 16 +#define NRS_POL_ARG_MAX 16 + +struct ptlrpc_nrs_pol_desc; + +/** + * Service compatibility predicate; this determines whether a policy is adequate + * for handling RPCs of a particular PTLRPC service. + * + * XXX:This should give the same result during policy registration and + * unregistration, and for all partitions of a service; so the result should not + * depend on temporal service or other properties, that may influence the + * result. + */ +typedef bool (*nrs_pol_desc_compat_t)(const struct ptlrpc_service *svc, + const struct ptlrpc_nrs_pol_desc *desc); + +struct ptlrpc_nrs_pol_conf { + /** + * Human-readable policy name + */ + char nc_name[NRS_POL_NAME_MAX]; + /** + * NRS operations for this policy + */ + const struct ptlrpc_nrs_pol_ops *nc_ops; + /** + * Service compatibility predicate + */ + nrs_pol_desc_compat_t nc_compat; + /** + * Set for policies that support a single ptlrpc service, i.e. ones that + * have \a pd_compat set to nrs_policy_compat_one(). The variable value + * depicts the name of the single service that such policies are + * compatible with. + */ + const char *nc_compat_svc_name; + /** + * Owner module for this policy descriptor; policies registering from a + * different module to the one the NRS framework is held within + * (currently ptlrpc), should set this field to THIS_MODULE. + */ + struct module *nc_owner; + /** + * Policy registration flags; a bitmask of \e nrs_policy_flags + */ + unsigned int nc_flags; +}; + +/** + * NRS policy registering descriptor + * + * Is used to hold a description of a policy that can be passed to NRS core in + * order to register the policy with NRS heads in different PTLRPC services. + */ +struct ptlrpc_nrs_pol_desc { + /** + * Human-readable policy name + */ + char pd_name[NRS_POL_NAME_MAX]; + /** + * Link into nrs_core::nrs_policies + */ + struct list_head pd_list; + /** + * NRS operations for this policy + */ + const struct ptlrpc_nrs_pol_ops *pd_ops; + /** + * Service compatibility predicate + */ + nrs_pol_desc_compat_t pd_compat; + /** + * Set for policies that are compatible with only one PTLRPC service. + * + * \see ptlrpc_nrs_pol_conf::nc_compat_svc_name + */ + const char *pd_compat_svc_name; + /** + * Owner module for this policy descriptor. + * + * We need to hold a reference to the module whenever we might make use + * of any of the module's contents, i.e. + * - If one or more instances of the policy are at a state where they + * might be handling a request, i.e. + * ptlrpc_nrs_pol_state::NRS_POL_STATE_STARTED or + * ptlrpc_nrs_pol_state::NRS_POL_STATE_STOPPING as we will have to + * call into the policy's ptlrpc_nrs_pol_ops() handlers. A reference + * is taken on the module when + * \e ptlrpc_nrs_pol_desc::pd_refs becomes 1, and released when it + * becomes 0, so that we hold only one reference to the module maximum + * at any time. + * + * We do not need to hold a reference to the module, even though we + * might use code and data from the module, in the following cases: + * - During external policy registration, because this should happen in + * the module's init() function, in which case the module is safe from + * removal because a reference is being held on the module by the + * kernel, and iirc kmod (and I guess module-init-tools also) will + * serialize any racing processes properly anyway. + * - During external policy unregistration, because this should happen + * in a module's exit() function, and any attempts to start a policy + * instance would need to take a reference on the module, and this is + * not possible once we have reached the point where the exit() + * handler is called. + * - During service registration and unregistration, as service setup + * and cleanup, and policy registration, unregistration and policy + * instance starting, are serialized by \e nrs_core::nrs_mutex, so + * as long as users adhere to the convention of registering policies + * in init() and unregistering them in module exit() functions, there + * should not be a race between these operations. + * - During any policy-specific lprocfs operations, because a reference + * is held by the kernel on a proc entry that has been entered by a + * syscall, so as long as proc entries are removed during + * unregistration time, then unregistration and lprocfs operations + * will be properly serialized. + */ + struct module *pd_owner; + /** + * Bitmask of \e nrs_policy_flags + */ + unsigned int pd_flags; + /** + * # of references on this descriptor + */ + atomic_t pd_refs; +}; + +/** + * NRS policy state + * + * Policies transition from one state to the other during their lifetime + */ +enum ptlrpc_nrs_pol_state { + /** + * Not a valid policy state. + */ + NRS_POL_STATE_INVALID, + /** + * Policies are at this state either at the start of their life, or + * transition here when the user selects a different policy to act + * as the primary one. + */ + NRS_POL_STATE_STOPPED, + /** + * Policy is progress of stopping + */ + NRS_POL_STATE_STOPPING, + /** + * Policy is in progress of starting + */ + NRS_POL_STATE_STARTING, + /** + * A policy is in this state in two cases: + * - it is the fallback policy, which is always in this state. + * - it has been activated by the user; i.e. it is the primary policy, + */ + NRS_POL_STATE_STARTED, +}; + +/** + * NRS policy information + * + * Used for obtaining information for the status of a policy via lprocfs + */ +struct ptlrpc_nrs_pol_info { + /** + * Policy name + */ + char pi_name[NRS_POL_NAME_MAX]; + /** + * Policy argument + */ + char pi_arg[NRS_POL_ARG_MAX]; + /** + * Current policy state + */ + enum ptlrpc_nrs_pol_state pi_state; + /** + * # RPCs enqueued for later dispatching by the policy + */ + long pi_req_queued; + /** + * # RPCs started for dispatch by the policy + */ + long pi_req_started; + /** + * Is this a fallback policy? + */ + unsigned pi_fallback:1; +}; + +/** + * NRS policy + * + * There is one instance of this for each policy in each NRS head of each + * PTLRPC service partition. + */ +struct ptlrpc_nrs_policy { + /** + * Linkage into the NRS head's list of policies, + * ptlrpc_nrs:nrs_policy_list + */ + struct list_head pol_list; + /** + * Linkage into the NRS head's list of policies with enqueued + * requests ptlrpc_nrs:nrs_policy_queued + */ + struct list_head pol_list_queued; + /** + * Current state of this policy + */ + enum ptlrpc_nrs_pol_state pol_state; + /** + * Bitmask of nrs_policy_flags + */ + unsigned int pol_flags; + /** + * # RPCs enqueued for later dispatching by the policy + */ + long pol_req_queued; + /** + * # RPCs started for dispatch by the policy + */ + long pol_req_started; + /** + * Usage Reference count taken on the policy instance + */ + long pol_ref; + /** + * Human-readable policy argument + */ + char pol_arg[NRS_POL_ARG_MAX]; + /** + * The NRS head this policy has been created at + */ + struct ptlrpc_nrs *pol_nrs; + /** + * Private policy data; varies by policy type + */ + void *pol_private; + /** + * Policy descriptor for this policy instance. + */ + struct ptlrpc_nrs_pol_desc *pol_desc; +}; + +/** + * NRS resource + * + * Resources are embedded into two types of NRS entities: + * - Inside NRS policies, in the policy's private data in + * ptlrpc_nrs_policy::pol_private + * - In objects that act as prime-level scheduling entities in different NRS + * policies; e.g. on a policy that performs round robin or similar order + * scheduling across client NIDs, there would be one NRS resource per unique + * client NID. On a policy which performs round robin scheduling across + * backend filesystem objects, there would be one resource associated with + * each of the backend filesystem objects partaking in the scheduling + * performed by the policy. + * + * NRS resources share a parent-child relationship, in which resources embedded + * in policy instances are the parent entities, with all scheduling entities + * a policy schedules across being the children, thus forming a simple resource + * hierarchy. This hierarchy may be extended with one or more levels in the + * future if the ability to have more than one primary policy is added. + * + * Upon request initialization, references to the then active NRS policies are + * taken and used to later handle the dispatching of the request with one of + * these policies. + * + * \see nrs_resource_get_safe() + * \see ptlrpc_nrs_req_add() + */ +struct ptlrpc_nrs_resource { + /** + * This NRS resource's parent; is NULL for resources embedded in NRS + * policy instances; i.e. those are top-level ones. + */ + struct ptlrpc_nrs_resource *res_parent; + /** + * The policy associated with this resource. + */ + struct ptlrpc_nrs_policy *res_policy; +}; + +enum { + NRS_RES_FALLBACK, + NRS_RES_PRIMARY, + NRS_RES_MAX +}; + +#include "lustre_nrs_fifo.h" + +/** + * NRS request + * + * Instances of this object exist embedded within ptlrpc_request; the main + * purpose of this object is to hold references to the request's resources + * for the lifetime of the request, and to hold properties that policies use + * use for determining the request's scheduling priority. + **/ +struct ptlrpc_nrs_request { + /** + * The request's resource hierarchy. + */ + struct ptlrpc_nrs_resource *nr_res_ptrs[NRS_RES_MAX]; + /** + * Index into ptlrpc_nrs_request::nr_res_ptrs of the resource of the + * policy that was used to enqueue the request. + * + * \see nrs_request_enqueue() + */ + unsigned int nr_res_idx; + unsigned int nr_initialized:1; + unsigned int nr_enqueued:1; + unsigned int nr_started:1; + unsigned int nr_finalized:1; + + /** + * Policy-specific fields, used for determining a request's scheduling + * priority, and other supporting functionality. + */ + union { + /** + * Fields for the FIFO policy + */ + struct nrs_fifo_req fifo; + } nr_u; + /** + * Externally-registering policies may want to use this to allocate + * their own request properties. + */ + void *ext; +}; + +/** @} nrs */ +#endif |