Linux Virtualization - Aug 2010 - [PATCH 5/6] staging: hv: Increased storvsc ringbuffer and max_io_requests

From: Hank Janssen <hjanssen at microsoft.com>

Increased storvsc ringbuffer and max_io_requests. This now more closely mimics 
the numbers on Hyper-V. And will allow more IO requests to take place for the
SCSI driver.

Signed-off-by:Hank Janssen <hjanssen at microsoft.com>
Signed-off-by:Haiyang Zhang <haiyangz at microsoft.com> 

---
 drivers/staging/hv/storvsc_api.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/hv/storvsc_api.h b/drivers/staging/hv/storvsc_api.h
index 0063bde..8505a1c 100644
--- a/drivers/staging/hv/storvsc_api.h
+++ b/drivers/staging/hv/storvsc_api.h
@@ -28,10 +28,10 @@
 #include "vmbus_api.h"
 
 /* Defines */
-#define STORVSC_RING_BUFFER_SIZE			(10*PAGE_SIZE)
+#define STORVSC_RING_BUFFER_SIZE			(20*PAGE_SIZE)
 #define BLKVSC_RING_BUFFER_SIZE				(20*PAGE_SIZE)
 
-#define STORVSC_MAX_IO_REQUESTS				64
+#define STORVSC_MAX_IO_REQUESTS				128
 
 /*
  * In Hyper-V, each port/path/target maps to 1 scsi host adapter.  In
--
1.6.0.2

On Tue, Aug 03, 2010 at 05:31:55PM +0000, Hank Janssen
wrote:
> From: Hank Janssen <hjanssen at microsoft.com>
> 
> Increased storvsc ringbuffer and max_io_requests. This now more closely
mimics
> the numbers on Hyper-V.
What do you mean by this?  The max provided by the hypervisor?
> And will allow more IO requests to take place for the SCSI driver.
Which means what, better throughput?  Or just more outstanding requests
and the same speed overall?

thanks,

greg k-h

On Tue, Aug 03, 2010 at 05:31:55PM +0000, Hank Janssen
wrote:
> From: Hank Janssen <hjanssen at microsoft.com>
> 
> Increased storvsc ringbuffer and max_io_requests. This now more closely
mimics
> the numbers on Hyper-V. And will allow more IO requests to take place for
the SCSI driver.
> 
> Signed-off-by:Hank Janssen <hjanssen at microsoft.com>
> Signed-off-by:Haiyang Zhang <haiyangz at microsoft.com> 
Again with the trailing spaces :(

>>And than Greg KH spoke these words:
>>On Tue, Aug 03, 2010 at 05:31:55PM +0000, Hank Janssen wrote:
> >From: Hank Janssen <hjanssen at microsoft.com>
> >
> >Increased storvsc ringbuffer and max_io_requests. This now more 
> >closely mimics the numbers on Hyper-V.
>
>What do you mean by this?  The max provided by the hypervisor?
Max_IO is set to double from what it was before, Hyper-V allows it and
We have had appliance builder requests to see if it was a problem to increase
The number.

Ringbuffer size for storvsc is now increased because I have seen 
A few buffer problems on extremely busy systems. They where 
Set pretty low before. And since max_io_requests is increased I
Really needed to increase the buffer as well.
>> And will allow more IO requests to take place for the SCSI driver.
>
>Which means what, better throughput?  Or just more outstanding requests and
the same speed overall?
It means better throughput of high load systems, else you get buffer
Contention. 

Thanks,

Hank.

On Wed, Aug 04, 2010 at 03:23:09AM +0000, Hank Janssen
wrote:
> 
> >>And than Greg KH spoke these words:
> >>On Tue, Aug 03, 2010 at 05:31:55PM +0000, Hank Janssen wrote:
> > >From: Hank Janssen <hjanssen at microsoft.com>
> > >
> > >Increased storvsc ringbuffer and max_io_requests. This now more 
> > >closely mimics the numbers on Hyper-V.
> >
> >What do you mean by this?  The max provided by the hypervisor?
> 
> Max_IO is set to double from what it was before, Hyper-V allows it and
> We have had appliance builder requests to see if it was a problem to
increase
> The number.
> 
> Ringbuffer size for storvsc is now increased because I have seen 
> A few buffer problems on extremely busy systems. They where 
> Set pretty low before. And since max_io_requests is increased I
> Really needed to increase the buffer as well.
> 
> >> And will allow more IO requests to take place for the SCSI driver.
> >
> >Which means what, better throughput?  Or just more outstanding requests
and the same speed overall?
> 
> It means better throughput of high load systems, else you get buffer
> Contention. 
All good, care to included this in the changelog comment when you resend
this whole series?

thanks,

greg k-h