ahci: enable full queue depth of 32

This changes the AHCI queue depth from 31 to 32, as libata now
fully supports it. Now regular IO requests can utilize the full
tag space of SATA, not just 31. For IOPS constrained workloads,
this can result in a ~3% bump in performance.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 4356ef1d28a88f66be04f5e431e9c55d768bb866..6712570a8816488171632162dc85d950e174daed 100644 (file)
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -384,7 +384,7 @@ extern struct device_attribute *ahci_sdev_attrs[];
  */
 #define AHCI_SHT(drv_name)                                             \
        ATA_NCQ_SHT(drv_name),                                          \
-       .can_queue              = AHCI_MAX_CMDS - 1,                    \
+       .can_queue              = AHCI_MAX_CMDS,                        \
        .sg_tablesize           = AHCI_MAX_SG,                          \
        .dma_boundary           = AHCI_DMA_BOUNDARY,                    \
        .shost_attrs            = ahci_shost_attrs,                     \