freebsd-skq/sys/geom/sched/g_sched.h
pfg a82e3a8b24 sys/geom: adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
2017-11-27 15:17:37 +00:00

128 lines
4.3 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2009-2010 Fabio Checconi
* Copyright (c) 2009-2010 Luigi Rizzo, Universita` di Pisa
* All rights reserved.
*
* 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 AUTHORS 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 AUTHORS 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.
*/
#ifndef _G_SCHED_H_
#define _G_SCHED_H_
/*
* $Id$
* $FreeBSD$
*
* Header for the geom_sched class (userland library and kernel part).
* See g_sched.c for documentation.
* The userland code only needs the three G_SCHED_* values below.
*/
#define G_SCHED_CLASS_NAME "SCHED"
#define G_SCHED_VERSION 0
#define G_SCHED_SUFFIX ".sched."
#ifdef _KERNEL
#define G_SCHED_DEBUG(lvl, ...) do { \
if (me.gs_debug >= (lvl)) { \
printf("GEOM_SCHED"); \
if (me.gs_debug > 0) \
printf("[%u]", lvl); \
printf(": "); \
printf(__VA_ARGS__); \
printf("\n"); \
} \
} while (0)
#define G_SCHED_LOGREQ(bp, ...) do { \
if (me.gs_debug >= 2) { \
printf("GEOM_SCHED[2]: "); \
printf(__VA_ARGS__); \
printf(" "); \
g_print_bio(bp); \
printf("\n"); \
} \
} while (0)
LIST_HEAD(g_hash, g_sched_class);
/*
* Descriptor of a scheduler.
* In addition to the obvious fields, sc_flushing and sc_pending
* support dynamic switching of scheduling algorithm.
* Normally, sc_flushing is 0, and requests that are scheduled are
* also added to the sc_pending queue, and removed when we receive
* the 'done' event.
*
* When we are transparently inserted on an existing provider,
* sc_proxying is set. The detach procedure is slightly different.
*
* When switching schedulers, sc_flushing is set so requests bypass us,
* and at the same time we update the pointer in the pending bios
* to ignore us when they return up.
* XXX it would be more efficient to implement sc_pending with
* a generation number: the softc generation is increased when
* we change scheduling algorithm, we store the current generation
* number in the pending bios, and when they come back we ignore
* the done() call if the generation number do not match.
*/
struct g_sched_softc {
/*
* Generic fields used by any scheduling algorithm:
* a mutex, the class descriptor, flags, list of pending
* requests (used when flushing the module) and support
* for hash tables where we store per-flow queues.
*/
struct mtx sc_mtx;
struct g_gsched *sc_gsched; /* Scheduler descriptor. */
int sc_pending; /* Pending requests. */
int sc_flags; /* Various flags. */
/*
* Hash tables to store per-flow queues are generally useful
* so we handle them in the common code.
* sc_hash and sc_mask are parameters of the hash table,
* the last two fields are used to periodically remove
* expired items from the hash table.
*/
struct g_hash *sc_hash;
u_long sc_mask;
int sc_flush_ticks; /* Next tick for a flush. */
int sc_flush_bucket; /* Next bucket to flush. */
/*
* Pointer to the algorithm's private data, which is the value
* returned by sc_gsched->gs_init() . A NULL here means failure.
* XXX intptr_t might be more appropriate.
*/
void *sc_data;
};
#define G_SCHED_PROXYING 1
#define G_SCHED_FLUSHING 2
#endif /* _KERNEL */
#endif /* _G_SCHED_H_ */