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scsi: add use_cmd_list flag

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Add a use_cmd_list flag in struct Scsi_Host to request keeping track of
all outstanding commands per device.

Default behaviour is not to keep track of cmd_list per sdev, as this may
introduce lock contention. (overhead is more on multi-node NUMA.), and
only enable it on the two drivers that need it.

Signed-off-by: Kashyap Desai <kashyap.desai@avagotech.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Kashyap.Desai@avagotech.com 2014-08-20 19:24:33 +05:30 committed by Christoph Hellwig
parent 2eefd57b97
commit 64bdcbc449
4 changed files with 15 additions and 12 deletions
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1
drivers/scsi/aacraid/linit.c
View file

@ -1152,6 +1152,7 @@ static int aac_probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
shost->irq = pdev->irq;
shost->unique_id = unique_id;
shost->max_cmd_len = 16;
shost->use_cmd_list = 1;
aac = (struct aac_dev *)shost->hostdata;
aac->base_start = pci_resource_start(pdev, 0);

1
drivers/scsi/dpt_i2o.c
View file

@ -2363,6 +2363,7 @@ static s32 adpt_scsi_host_alloc(adpt_hba* pHba, struct scsi_host_template *sht)
host->unique_id = (u32)sys_tbl_pa + pHba->unit;
host->sg_tablesize = pHba->sg_tablesize;
host->can_queue = pHba->post_fifo_size;
host->use_cmd_list = 1;
return 0;
}

24
drivers/scsi/scsi_lib.c
View file

@ -645,16 +645,18 @@ static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
{
struct scsi_device *sdev = cmd->device;
struct Scsi_Host *shost = sdev->host;
unsigned long flags;
BUG_ON(list_empty(&cmd->list));
scsi_mq_free_sgtables(cmd);
scsi_uninit_cmd(cmd);
spin_lock_irqsave(&sdev->list_lock, flags);
list_del_init(&cmd->list);
spin_unlock_irqrestore(&sdev->list_lock, flags);
if (shost->use_cmd_list) {
BUG_ON(list_empty(&cmd->list));
spin_lock_irqsave(&sdev->list_lock, flags);
list_del_init(&cmd->list);
spin_unlock_irqrestore(&sdev->list_lock, flags);
}
}
/*
@ -1815,13 +1817,11 @@ static int scsi_mq_prep_fn(struct request *req)
INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
cmd->jiffies_at_alloc = jiffies;
/*
* XXX: cmd_list lookups are only used by two drivers, try to get
* rid of this list in common code.
*/
spin_lock_irq(&sdev->list_lock);
list_add_tail(&cmd->list, &sdev->cmd_list);
spin_unlock_irq(&sdev->list_lock);
if (shost->use_cmd_list) {
spin_lock_irq(&sdev->list_lock);
list_add_tail(&cmd->list, &sdev->cmd_list);
spin_unlock_irq(&sdev->list_lock);
}
sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
cmd->sdb.table.sgl = sg;

1
include/scsi/scsi_host.h
View file

@ -680,6 +680,7 @@ struct Scsi_Host {
unsigned no_write_same:1;
unsigned use_blk_mq:1;
unsigned use_cmd_list:1;
/*
* Optional work queue to be utilized by the transport