On Tue, Sep 14, 2021 at 4:25 PM Dmitry Bogdanov <d.bogdanov@xxxxxxxxx> wrote:
>
> Under session level spinlock node->active_ios_lock in
> efct_scsi_io_alloc() there is a getting other spinlock of port level.
> That lead to competition between sessions and even between IOs in the
> same session due too much instructions under spinlock.
>
> This change reduces spinlock area just to active_ios list for which
> active_ios_lock is intended.
> Spinlock CPU usage is decreased from 18% down to 13% in efct driver.
> IOPS are increased from 220 kIOPS upto 264 kIOPS for one lun on my setup.
>
> Reviewed-by: Roman Bolshakov <r.bolshakov@xxxxxxxxx>
> Signed-off-by: Dmitry Bogdanov <d.bogdanov@xxxxxxxxx>
> ---
> drivers/scsi/elx/efct/efct_scsi.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/elx/efct/efct_scsi.c b/drivers/scsi/elx/efct/efct_scsi.c
> index 40fb3a724c76..8535bb7eabd8 100644
> --- a/drivers/scsi/elx/efct/efct_scsi.c
> +++ b/drivers/scsi/elx/efct/efct_scsi.c
> @@ -38,8 +38,6 @@ efct_scsi_io_alloc(struct efct_node *node)
>
> xport = efct->xport;
>
> - spin_lock_irqsave(&node->active_ios_lock, flags);
> -
> io = efct_io_pool_io_alloc(efct->xport->io_pool);
> if (!io) {
> efc_log_err(efct, "IO alloc Failed\n");
> @@ -66,6 +64,7 @@ efct_scsi_io_alloc(struct efct_node *node)
>
> /* Add to node's active_ios list */
> INIT_LIST_HEAD(&io->list_entry);
> + spin_lock_irqsave(&node->active_ios_lock, flags);
> list_add(&io->list_entry, &node->active_ios);
>
> spin_unlock_irqrestore(&node->active_ios_lock, flags);
> --
> 2.25.1
>
Looks good. Thanks.
Reviewed-by: Ram Vegesna <ram.vegesna@xxxxxxxxxxxx>
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