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isci: cleanup/optimize pool implementation 

The circ_buf macros are ~6% faster, as measured by perf, because they take
advantage of power-of-two math assumptions i.e. no test and branch for
rollover. Their semantics are clearer than the hidden side effects in pool.h
(like sci_pool_get() which hides an assignment).

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2011-06-07 18:50:55 -07:00
parent 9b917987fd
commit ac668c6970
4 changed files with 56 additions and 231 deletions
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75
drivers/scsi/isci/host.c
View File

@ -52,6 +52,7 @@
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <linux/circ_buf.h>
#include <linux/device.h>
#include <scsi/sas.h>
#include "host.h"
@ -1054,6 +1055,33 @@ done:
spin_unlock_irqrestore(&ihost->scic_lock, flags);
}
static void isci_tci_free(struct isci_host *ihost, u16 tci)
{
u16 tail = ihost->tci_tail & (SCI_MAX_IO_REQUESTS-1);
ihost->tci_pool[tail] = tci;
ihost->tci_tail = tail + 1;
}
static u16 isci_tci_alloc(struct isci_host *ihost)
{
u16 head = ihost->tci_head & (SCI_MAX_IO_REQUESTS-1);
u16 tci = ihost->tci_pool[head];
ihost->tci_head = head + 1;
return tci;
}
static u16 isci_tci_active(struct isci_host *ihost)
{
return CIRC_CNT(ihost->tci_head, ihost->tci_tail, SCI_MAX_IO_REQUESTS);
}
static u16 isci_tci_space(struct isci_host *ihost)
{
return CIRC_SPACE(ihost->tci_head, ihost->tci_tail, SCI_MAX_IO_REQUESTS);
}
static enum sci_status scic_controller_start(struct scic_sds_controller *scic,
u32 timeout)
{
@ -1069,9 +1097,11 @@ static enum sci_status scic_controller_start(struct scic_sds_controller *scic,
}
/* Build the TCi free pool */
sci_pool_initialize(scic->tci_pool);
BUILD_BUG_ON(SCI_MAX_IO_REQUESTS > 1 << sizeof(ihost->tci_pool[0]) * 8);
ihost->tci_head = 0;
ihost->tci_tail = 0;
for (index = 0; index < scic->task_context_entries; index++)
sci_pool_put(scic->tci_pool, index);
isci_tci_free(ihost, index);
/* Build the RNi free pool */
scic_sds_remote_node_table_initialize(
@ -3063,18 +3093,17 @@ enum sci_task_status scic_controller_start_task(
* currently available tags to be allocated. All return other values indicate a
* legitimate tag.
*/
u16 scic_controller_allocate_io_tag(
struct scic_sds_controller *scic)
u16 scic_controller_allocate_io_tag(struct scic_sds_controller *scic)
{
u16 task_context;
u16 sequence_count;
struct isci_host *ihost = scic_to_ihost(scic);
u16 tci;
u16 seq;
if (!sci_pool_empty(scic->tci_pool)) {
sci_pool_get(scic->tci_pool, task_context);
if (isci_tci_space(ihost)) {
tci = isci_tci_alloc(ihost);
seq = scic->io_request_sequence[tci];
sequence_count = scic->io_request_sequence[task_context];
return scic_sds_io_tag_construct(sequence_count, task_context);
return scic_sds_io_tag_construct(seq, tci);
}
return SCI_CONTROLLER_INVALID_IO_TAG;
@ -3105,10 +3134,10 @@ u16 scic_controller_allocate_io_tag(
* tags. SCI_FAILURE_INVALID_IO_TAG This value is returned if the supplied tag
* is not a valid IO tag value.
*/
enum sci_status scic_controller_free_io_tag(
struct scic_sds_controller *scic,
u16 io_tag)
enum sci_status scic_controller_free_io_tag(struct scic_sds_controller *scic,
u16 io_tag)
{
struct isci_host *ihost = scic_to_ihost(scic);
u16 sequence;
u16 index;
@ -3117,18 +3146,16 @@ enum sci_status scic_controller_free_io_tag(
sequence = scic_sds_io_tag_get_sequence(io_tag);
index = scic_sds_io_tag_get_index(io_tag);
if (!sci_pool_full(scic->tci_pool)) {
if (sequence == scic->io_request_sequence[index]) {
scic_sds_io_sequence_increment(
scic->io_request_sequence[index]);
/* prevent tail from passing head */
if (isci_tci_active(ihost) == 0)
return SCI_FAILURE_INVALID_IO_TAG;
sci_pool_put(scic->tci_pool, index);
if (sequence == scic->io_request_sequence[index]) {
scic_sds_io_sequence_increment(scic->io_request_sequence[index]);
return SCI_SUCCESS;
}
isci_tci_free(ihost, index);
return SCI_SUCCESS;
}
return SCI_FAILURE_INVALID_IO_TAG;
}

12
drivers/scsi/isci/host.h
View File

@ -57,7 +57,6 @@
#include "remote_device.h"
#include "phy.h"
#include "pool.h"
#include "isci.h"
#include "remote_node_table.h"
#include "registers.h"
@ -179,11 +178,6 @@ struct scic_sds_controller {
*/
struct scic_remote_node_table available_remote_nodes;
/**
* This field is the TCi pool used to manage the task context index.
*/
SCI_POOL_CREATE(tci_pool, u16, SCI_MAX_IO_REQUESTS);
/**
* This filed is the struct scic_power_control data used to controll when direct
* attached devices can consume power.
@ -310,6 +304,10 @@ struct scic_sds_controller {
struct isci_host {
struct scic_sds_controller sci;
u16 tci_head;
u16 tci_tail;
u16 tci_pool[SCI_MAX_IO_REQUESTS];
union scic_oem_parameters oem_parameters;
int id; /* unique within a given pci device */
@ -423,8 +421,6 @@ enum scic_sds_controller_states {
SCIC_FAILED,
};
/**
* struct isci_pci_info - This class represents the pci function containing the
* controllers. Depending on PCI SKU, there could be up to 2 controllers in

1
drivers/scsi/isci/isci.h
View File

@ -112,6 +112,7 @@ static inline void check_sizes(void)
BUILD_BUG_ON_NOT_POWER_OF_2(SCU_MAX_UNSOLICITED_FRAMES);
BUILD_BUG_ON_NOT_POWER_OF_2(SCU_MAX_COMPLETION_QUEUE_ENTRIES);
BUILD_BUG_ON(SCU_MAX_UNSOLICITED_FRAMES > SCU_ABSOLUTE_MAX_UNSOLICITED_FRAMES);
BUILD_BUG_ON_NOT_POWER_OF_2(SCI_MAX_IO_REQUESTS);
}
/**

199
drivers/scsi/isci/pool.h
View File

@ -1,199 +0,0 @@
/*
* This file is provided under a dual BSD/GPLv2 license. When using or
* redistributing this file, you may do so under either license.
*
* GPL LICENSE SUMMARY
*
* Copyright(c) 2008 - 2011 Intel Corporation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License 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 for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
* The full GNU General Public License is included in this distribution
* in the file called LICENSE.GPL.
*
* BSD LICENSE
*
* Copyright(c) 2008 - 2011 Intel Corporation. All rights reserved.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* OWNER 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.
*/
/**
* This file contains the interface to the pool class. This class allows two
* different two different priority tasks to insert and remove items from
* the free pool. The user of the pool is expected to evaluate the pool
* condition empty before a get operation and pool condition full before a
* put operation. Methods Provided: - sci_pool_create() -
* sci_pool_initialize() - sci_pool_empty() - sci_pool_full() -
* sci_pool_get() - sci_pool_put()
*
*
*/
#ifndef _SCI_POOL_H_
#define _SCI_POOL_H_
/**
* SCI_POOL_INCREMENT() -
*
* Private operation for the pool
*/
#define SCI_POOL_INCREMENT(pool, index) \
(((index) + 1) == (pool).size ? 0 : (index) + 1)
/**
* SCI_POOL_CREATE() -
*
* This creates a pool structure of pool_name. The members in the pool are of
* type with number of elements equal to size.
*/
#define SCI_POOL_CREATE(pool_name, type, pool_size) \
struct \
{ \
u32 size; \
u32 get; \
u32 put; \
type array[(pool_size) + 1]; \
} pool_name
/**
* sci_pool_empty() -
*
* This macro evaluates the pool and returns true if the pool is empty. If the
* pool is empty the user should not perform any get operation on the pool.
*/
#define sci_pool_empty(pool) \
((pool).get == (pool).put)
/**
* sci_pool_full() -
*
* This macro evaluates the pool and returns true if the pool is full. If the
* pool is full the user should not perform any put operation.
*/
#define sci_pool_full(pool) \
(SCI_POOL_INCREMENT(pool, (pool).put) == (pool).get)
/**
* sci_pool_size() -
*
* This macro returns the size of the pool created. The internal size of the
* pool is actually 1 larger then necessary in order to ensure get and put
* pointers can be written simultaneously by different users. As a result,
* this macro subtracts 1 from the internal size
*/
#define sci_pool_size(pool) \
((pool).size - 1)
/**
* sci_pool_count() -
*
* This macro indicates the number of elements currently contained in the pool.
*/
#define sci_pool_count(pool) \
(\
sci_pool_empty((pool)) \
? 0 \
: (\
sci_pool_full((pool)) \
? sci_pool_size((pool)) \
: (\
(pool).get > (pool).put \
? ((pool).size - (pool).get + (pool).put) \
: ((pool).put - (pool).get) \
) \
) \
)
/**
* sci_pool_initialize() -
*
* This macro initializes the pool to an empty condition.
*/
#define sci_pool_initialize(pool) \
{ \
(pool).size = (sizeof((pool).array) / sizeof((pool).array[0])); \
(pool).get = 0; \
(pool).put = 0; \
}
/**
* sci_pool_get() -
*
* This macro will get the next free element from the pool. This should only be
* called if the pool is not empty.
*/
#define sci_pool_get(pool, my_value) \
{ \
(my_value) = (pool).array[(pool).get]; \
(pool).get = SCI_POOL_INCREMENT((pool), (pool).get); \
}
/**
* sci_pool_put() -
*
* This macro will put the value into the pool. This should only be called if
* the pool is not full.
*/
#define sci_pool_put(pool, value) \
{ \
(pool).array[(pool).put] = (value); \
(pool).put = SCI_POOL_INCREMENT((pool), (pool).put); \
}
/**
* sci_pool_erase() -
*
* This macro will search the pool and remove any elements in the pool matching
* the supplied value. This method can only be utilized on pools
*/
#define sci_pool_erase(pool, type, value) \
{ \
type tmp_value; \
u32 index; \
u32 element_count = sci_pool_count((pool)); \
\
for (index = 0; index < element_count; index++) { \
sci_pool_get((pool), tmp_value); \
if (tmp_value != (value)) \
sci_pool_put((pool), tmp_value); \
} \
}
#endif /* _SCI_POOL_H_ */