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| author | Kashyap.Desai@avagotech.com <Kashyap.Desai@avagotech.com> | 2014-08-20 19:24:33 +0530 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2014-09-15 16:01:58 -0700 |
| commit | 64bdcbc449105377dd60c8da97cfc1663b39562c (patch) | |
| tree | be79dd9fe4dfd101dc68ed5ee6d0d53ce2efad09 /drivers/scsi/scsi_lib.c | |
| parent | 2eefd57b97609949ae40952da2dea338e7d9a125 (diff) | |
| download | linux-stable-64bdcbc449105377dd60c8da97cfc1663b39562c.tar.gz linux-stable-64bdcbc449105377dd60c8da97cfc1663b39562c.tar.bz2 linux-stable-64bdcbc449105377dd60c8da97cfc1663b39562c.zip | |
scsi: add use_cmd_list flag
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>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index d837dc180522..b9a8ddd77eef 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -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; |