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freebsd/sys/cam/cam_sim.h
Alexander Motin 227d67aa54 Merge CAM locking changes from the projects/camlock branch to radically
reduce lock congestion and improve SMP scalability of the SCSI/ATA stack,
preparing the ground for the coming next GEOM direct dispatch support.

Replace big per-SIM locks with bunch of smaller ones:
 - per-LUN locks to protect device and peripheral drivers state;
 - per-target locks to protect list of LUNs on target;
 - per-bus locks to protect reference counting;
 - per-send queue locks to protect queue of CCBs to be sent;
 - per-done queue locks to protect queue of completed CCBs;
 - remaining per-SIM locks now protect only HBA driver internals.

While holding LUN lock it is allowed (while not recommended for performance
reasons) to take SIM lock.  The opposite acquisition order is forbidden.
All the other locks are leaf locks, that can be taken anywhere, but should
not be cascaded.  Many functions, such as: xpt_action(), xpt_done(),
xpt_async(), xpt_create_path(), etc. are no longer require (but allow) SIM
lock to be held.

To keep compatibility and solve cases where SIM lock can't be dropped, all
xpt_async() calls in addition to xpt_done() calls are queued to completion
threads for async processing in clean environment without SIM lock held.

Instead of single CAM SWI thread, used for commands completion processing
before, use multiple (depending on number of CPUs) threads.  Load balanced
between them using "hash" of the device B:T:L address.

HBA drivers that can drop SIM lock during completion processing and have
sufficient number of completion threads to efficiently scale to multiple
CPUs can use new function xpt_done_direct() to avoid extra context switch.
Make ahci(4) driver to use this mechanism depending on hardware setup.

Sponsored by:	iXsystems, Inc.
MFC after:	2 months
2013-10-21 12:00:26 +00:00

147 lines
4.5 KiB
C

/*-
* Data structures and definitions for SCSI Interface Modules (SIMs).
*
* Copyright (c) 1997 Justin T. Gibbs.
* 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,
* without modification, immediately at the beginning of the file.
* 2. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
#ifndef _CAM_CAM_SIM_H
#define _CAM_CAM_SIM_H 1
#ifdef _KERNEL
/*
* The sim driver creates a sim for each controller. The sim device
* queue is separately created in order to allow resource sharing between
* sims. For instance, a driver may create one sim for each channel of
* a multi-channel controller and use the same queue for each channel.
* In this way, the queue resources are shared across all the channels
* of the multi-channel controller.
*/
struct cam_sim;
struct cam_devq;
typedef void (*sim_action_func)(struct cam_sim *sim, union ccb *ccb);
typedef void (*sim_poll_func)(struct cam_sim *sim);
struct cam_devq * cam_simq_alloc(u_int32_t max_sim_transactions);
void cam_simq_free(struct cam_devq *devq);
struct cam_sim * cam_sim_alloc(sim_action_func sim_action,
sim_poll_func sim_poll,
const char *sim_name,
void *softc,
u_int32_t unit,
struct mtx *mtx,
int max_dev_transactions,
int max_tagged_dev_transactions,
struct cam_devq *queue);
void cam_sim_free(struct cam_sim *sim, int free_devq);
void cam_sim_hold(struct cam_sim *sim);
void cam_sim_release(struct cam_sim *sim);
/* Optional sim attributes may be set with these. */
void cam_sim_set_path(struct cam_sim *sim, u_int32_t path_id);
/* Convenience routines for accessing sim attributes. */
static __inline u_int32_t cam_sim_path(struct cam_sim *sim);
static __inline const char * cam_sim_name(struct cam_sim *sim);
static __inline void * cam_sim_softc(struct cam_sim *sim);
static __inline u_int32_t cam_sim_unit(struct cam_sim *sim);
static __inline u_int32_t cam_sim_bus(struct cam_sim *sim);
/* Generically useful offsets into the sim private area */
#define spriv_ptr0 sim_priv.entries[0].ptr
#define spriv_ptr1 sim_priv.entries[1].ptr
#define spriv_field0 sim_priv.entries[0].field
#define spriv_field1 sim_priv.entries[1].field
/*
* The sim driver should not access anything directly from this
* structure.
*/
struct cam_sim {
sim_action_func sim_action;
sim_poll_func sim_poll;
const char *sim_name;
void *softc;
struct mtx *mtx;
TAILQ_HEAD(, ccb_hdr) sim_doneq;
TAILQ_ENTRY(cam_sim) links;
u_int32_t path_id;/* The Boot device may set this to 0? */
u_int32_t unit_number;
u_int32_t bus_id;
int max_tagged_dev_openings;
int max_dev_openings;
u_int32_t flags;
#define CAM_SIM_REL_TIMEOUT_PENDING 0x01
#define CAM_SIM_MPSAFE 0x02
struct callout callout;
struct cam_devq *devq; /* Device Queue to use for this SIM */
int refcount; /* References to the SIM. */
};
#define CAM_SIM_LOCK(sim) mtx_lock((sim)->mtx)
#define CAM_SIM_UNLOCK(sim) mtx_unlock((sim)->mtx)
static __inline u_int32_t
cam_sim_path(struct cam_sim *sim)
{
return (sim->path_id);
}
static __inline const char *
cam_sim_name(struct cam_sim *sim)
{
return (sim->sim_name);
}
static __inline void *
cam_sim_softc(struct cam_sim *sim)
{
return (sim->softc);
}
static __inline u_int32_t
cam_sim_unit(struct cam_sim *sim)
{
return (sim->unit_number);
}
static __inline u_int32_t
cam_sim_bus(struct cam_sim *sim)
{
return (sim->bus_id);
}
#endif /* _KERNEL */
#endif /* _CAM_CAM_SIM_H */