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Some micro-optimizations by more cache friendly fields layouts

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git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@4812 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Vladislav Bolkhovitin
2013-03-26 00:18:06 +00:00
parent f9d666ace2
commit 829172f232
2 changed files with 57 additions and 45 deletions
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scst/include/scst.h
+41 -41
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@@ -1662,7 +1662,7 @@ struct scst_session {
* very beginning, because otherwise they can be missed during
* TM processing.
*/
struct list_head sess_cmd_list;
struct list_head sess_cmd_list ____cacheline_aligned_in_smp;
spinlock_t sess_list_lock; /* protects sess_cmd_list, etc */
@@ -2303,7 +2303,7 @@ struct scst_dev_registrant {
* SCST device
*/
struct scst_device {
unsigned short type; /* SCSI type of the device */
unsigned int type; /* SCSI type of the device */
/*************************************************************
** Dev's flags. Updates serialized by dev_lock or suspended
@@ -2311,16 +2311,16 @@ struct scst_device {
*************************************************************/
/* Set if dev is RESERVED */
unsigned short dev_reserved:1;
unsigned int dev_reserved:1;
/* Set if double reset UA is possible */
unsigned short dev_double_ua_possible:1;
unsigned int dev_double_ua_possible:1;
/* If set, dev is read only */
unsigned short dev_rd_only:1;
unsigned int dev_rd_only:1;
/* Set, if a strictly serialized cmd is waiting blocked */
unsigned short strictly_serialized_cmd_waiting:1;
unsigned int strictly_serialized_cmd_waiting:1;
/*
* Set, if this device is being unregistered. Useful to let sysfs
@@ -2328,7 +2328,7 @@ struct scst_device {
* possible deadlocks with their device unregistration waiting for
* their kobj last put.
*/
unsigned short dev_unregistering:1;
unsigned int dev_unregistering:1;
/**************************************************************/
@@ -2353,37 +2353,6 @@ struct scst_device {
/**************************************************************/
/*
* Device lock. Modified independently to the above fields, hence
* the alignment. Gcc reported to have a long standing bug, when
* it uses 64-bit memory accesses for int bit fields, so this
* alignment must be here to workaroud it.
*/
spinlock_t dev_lock __aligned(sizeof(long));
#ifdef CONFIG_SCST_PER_DEVICE_CMD_COUNT_LIMIT
/* How many cmds alive on this dev */
atomic_t dev_cmd_count;
#endif
/*
* How many times device was blocked for new cmds execution.
* Protected by dev_lock.
*/
int block_count;
/*
* How many there are "on_dev" commands, i.e. ones who passed
* scst_check_blocked_dev(). Protected by dev_lock.
*/
int on_dev_cmd_count;
/*
* How many threads are checking commands for PR allowance.
* Protected by dev_lock.
*/
int pr_readers_count;
/*
* Device block size and block shift if fixed size blocks used. Supposed
* to be read-only or serialized the same way as MODE pages changes.
@@ -2411,12 +2380,43 @@ struct scst_device {
/* Corresponding real SCSI device, could be NULL for virtual devices */
struct scsi_device *scsi_dev;
/* List of commands with lock, if dedicated threads are used */
struct scst_cmd_threads dev_cmd_threads;
/*
* Device lock. Modified independently to the above fields, hence
* the alignment. Gcc reported to have a long standing bug, when
* it uses 64-bit memory accesses for int bit fields, so this
* alignment must be here to workaroud it.
*/
spinlock_t dev_lock ____cacheline_aligned_in_smp;
#ifdef CONFIG_SCST_PER_DEVICE_CMD_COUNT_LIMIT
/* How many cmds alive on this dev */
atomic_t dev_cmd_count;
#endif
/*
* How many times device was blocked for new cmds execution.
* Protected by dev_lock.
*/
int block_count;
/*
* How many there are "on_dev" commands, i.e. ones who passed
* scst_check_blocked_dev(). Protected by dev_lock.
*/
int on_dev_cmd_count;
/*
* How many threads are checking commands for PR allowance.
* Protected by dev_lock.
*/
int pr_readers_count;
/* Memory limits for this device */
struct scst_mem_lim dev_mem_lim;
/* List of commands with lock, if dedicated threads are used */
struct scst_cmd_threads dev_cmd_threads;
/*************************************************************
** Persistent reservation fields. Protected by dev_pr_mutex.
*************************************************************/
@@ -2552,7 +2552,7 @@ struct scst_tgt_dev {
void *dh_priv;
/* How many cmds alive on this dev in this session */
atomic_t tgt_dev_cmd_count;
atomic_t tgt_dev_cmd_count ____cacheline_aligned_in_smp;
struct scst_order_data *curr_order_data;
struct scst_order_data tgt_dev_order_data;