[PATCH] ibmvscsi: Speed up kexec boot

[PATCH] ibmvscsi: Speed up kexec boot

[Anton Blanchard]

During kexec boot we call ibmvscsi_release_crq_queue() to tear down
the old CRQ from the previous kernel. ibmvscsi_release_crq_queue()
does this by calling H_FREE_CRQ. The hypervisor breaks this work
down so as limit the time spent in any one hcall, so we have to loop
until complete.

At the moment we delay 0.1 seconds between every H_FREE_CRQ call.
I see us calling H_FREE_CRQ 60 times on my box which means we
delayed a total of 6 seconds.

This delay is overkill, we are free to handle all busy return codes
from the hypervisor as we see fit. Cut the delay down to something
more reasonable - 1 ms. This improves my boot time by 6 seconds.

Fix the other places we have arbitrary 100 ms delays.

Signed-off-by: Anton Blanchard <anton@samba.org>
---

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index fa76440..ed7b52e 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -159,7 +159,7 @@ static void ibmvscsi_release_crq_queue(struct crq_queue *queue,
 	tasklet_kill(&hostdata->srp_task);
 	do {
 		if (rc)
-			msleep(100);
+			msleep(1);
 		rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
 	} while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
 	dma_unmap_single(hostdata->dev,
@@ -292,7 +292,7 @@ static int ibmvscsi_reset_crq_queue(struct crq_queue *queue,
 	/* Close the CRQ */
 	do {
 		if (rc)
-			msleep(100);
+			msleep(1);
 		rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
 	} while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
 
@@ -392,7 +392,7 @@ static int ibmvscsi_init_crq_queue(struct crq_queue *queue,
 	rc = 0;
 	do {
 		if (rc)
-			msleep(100);
+			msleep(1);
 		rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
 	} while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
       reg_crq_failed:
@@ -420,7 +420,7 @@ static int ibmvscsi_reenable_crq_queue(struct crq_queue *queue,
 	/* Re-enable the CRQ */
 	do {
 		if (rc)
-			msleep(100);
+			msleep(1);
 		rc = plpar_hcall_norets(H_ENABLE_CRQ, vdev->unit_address);
 	} while ((rc == H_IN_PROGRESS) || (rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
 

Re: [PATCH] ibmvscsi: Speed up kexec boot

[Anton Blanchard]

Hi,

> During kexec boot we call ibmvscsi_release_crq_queue() to tear down
> the old CRQ from the previous kernel. ibmvscsi_release_crq_queue()
> does this by calling H_FREE_CRQ. The hypervisor breaks this work
> down so as limit the time spent in any one hcall, so we have to loop
> until complete.
> 
> At the moment we delay 0.1 seconds between every H_FREE_CRQ call.
> I see us calling H_FREE_CRQ 60 times on my box which means we
> delayed a total of 6 seconds.
> 
> This delay is overkill, we are free to handle all busy return codes
> from the hypervisor as we see fit. Cut the delay down to something
> more reasonable - 1 ms. This improves my boot time by 6 seconds.
> 
> Fix the other places we have arbitrary 100 ms delays.

Checking in on this patch, 6 seconds is a decent chunk of our boot time
on KVM.

Anton

> Signed-off-by: Anton Blanchard <anton@samba.org>
> ---
> 
> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c
> b/drivers/scsi/ibmvscsi/ibmvscsi.c index fa76440..ed7b52e 100644
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -159,7 +159,7 @@ static void ibmvscsi_release_crq_queue(struct
> crq_queue *queue, tasklet_kill(&hostdata->srp_task);
>  	do {
>  		if (rc)
> -			msleep(100);
> +			msleep(1);
>  		rc = plpar_hcall_norets(H_FREE_CRQ,
> vdev->unit_address); } while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
>  	dma_unmap_single(hostdata->dev,
> @@ -292,7 +292,7 @@ static int ibmvscsi_reset_crq_queue(struct
> crq_queue *queue, /* Close the CRQ */
>  	do {
>  		if (rc)
> -			msleep(100);
> +			msleep(1);
>  		rc = plpar_hcall_norets(H_FREE_CRQ,
> vdev->unit_address); } while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
>  
> @@ -392,7 +392,7 @@ static int ibmvscsi_init_crq_queue(struct
> crq_queue *queue, rc = 0;
>  	do {
>  		if (rc)
> -			msleep(100);
> +			msleep(1);
>  		rc = plpar_hcall_norets(H_FREE_CRQ,
> vdev->unit_address); } while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
>        reg_crq_failed:
> @@ -420,7 +420,7 @@ static int ibmvscsi_reenable_crq_queue(struct
> crq_queue *queue, /* Re-enable the CRQ */
>  	do {
>  		if (rc)
> -			msleep(100);
> +			msleep(1);
>  		rc = plpar_hcall_norets(H_ENABLE_CRQ,
> vdev->unit_address); } while ((rc == H_IN_PROGRESS) || (rc == H_BUSY)
> || (H_IS_LONG_BUSY(rc)));