[SCSI] vmw_pvscsi: Add support for I/O requests coalescing.
This change allows pvscsi driver to coalesce I/O requests
before issuing them. The number of I/O's coalesced can be
dynamically configured based on the workload.
Signed-off-by: Rishi Mehta <rmehta@vmware.com>
Signed-off-by: Arvind Kumar <arvindkumar@vmware.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/vmw_pvscsi.c b/drivers/scsi/vmw_pvscsi.c
index 7c5abd7..b92ea94 100644
--- a/drivers/scsi/vmw_pvscsi.c
+++ b/drivers/scsi/vmw_pvscsi.c
@@ -72,6 +72,7 @@
bool use_msi;
bool use_msix;
bool use_msg;
+ bool use_req_threshold;
spinlock_t hw_lock;
@@ -109,6 +110,7 @@
static bool pvscsi_disable_msi;
static bool pvscsi_disable_msix;
static bool pvscsi_use_msg = true;
+static bool pvscsi_use_req_threshold = true;
#define PVSCSI_RW (S_IRUSR | S_IWUSR)
@@ -133,6 +135,10 @@
module_param_named(use_msg, pvscsi_use_msg, bool, PVSCSI_RW);
MODULE_PARM_DESC(use_msg, "Use msg ring when available - (default=1)");
+module_param_named(use_req_threshold, pvscsi_use_req_threshold,
+ bool, PVSCSI_RW);
+MODULE_PARM_DESC(use_req_threshold, "Use driver-based request coalescing if configured - (default=1)");
+
static const struct pci_device_id pvscsi_pci_tbl[] = {
{ PCI_VDEVICE(VMWARE, PCI_DEVICE_ID_VMWARE_PVSCSI) },
{ 0 }
@@ -282,10 +288,15 @@
static void pvscsi_kick_io(const struct pvscsi_adapter *adapter,
unsigned char op)
{
- if (scsi_is_rw(op))
- pvscsi_kick_rw_io(adapter);
- else
+ if (scsi_is_rw(op)) {
+ struct PVSCSIRingsState *s = adapter->rings_state;
+
+ if (!adapter->use_req_threshold ||
+ s->reqProdIdx - s->reqConsIdx >= s->reqCallThreshold)
+ pvscsi_kick_rw_io(adapter);
+ } else {
pvscsi_process_request_ring(adapter);
+ }
}
static void ll_adapter_reset(const struct pvscsi_adapter *adapter)
@@ -1077,6 +1088,34 @@
return 1;
}
+static bool pvscsi_setup_req_threshold(struct pvscsi_adapter *adapter,
+ bool enable)
+{
+ u32 val;
+
+ if (!pvscsi_use_req_threshold)
+ return false;
+
+ pvscsi_reg_write(adapter, PVSCSI_REG_OFFSET_COMMAND,
+ PVSCSI_CMD_SETUP_REQCALLTHRESHOLD);
+ val = pvscsi_reg_read(adapter, PVSCSI_REG_OFFSET_COMMAND_STATUS);
+ if (val == -1) {
+ printk(KERN_INFO "vmw_pvscsi: device does not support req_threshold\n");
+ return false;
+ } else {
+ struct PVSCSICmdDescSetupReqCall cmd_msg = { 0 };
+ cmd_msg.enable = enable;
+ printk(KERN_INFO
+ "vmw_pvscsi: %sabling reqCallThreshold\n",
+ enable ? "en" : "dis");
+ pvscsi_write_cmd_desc(adapter,
+ PVSCSI_CMD_SETUP_REQCALLTHRESHOLD,
+ &cmd_msg, sizeof(cmd_msg));
+ return pvscsi_reg_read(adapter,
+ PVSCSI_REG_OFFSET_COMMAND_STATUS) != 0;
+ }
+}
+
static irqreturn_t pvscsi_isr(int irq, void *devp)
{
struct pvscsi_adapter *adapter = devp;
@@ -1416,6 +1455,10 @@
flags = IRQF_SHARED;
}
+ adapter->use_req_threshold = pvscsi_setup_req_threshold(adapter, true);
+ printk(KERN_DEBUG "vmw_pvscsi: driver-based request coalescing %sabled\n",
+ adapter->use_req_threshold ? "en" : "dis");
+
error = request_irq(adapter->irq, pvscsi_isr, flags,
"vmw_pvscsi", adapter);
if (error) {