[PATCH 1/2] hpsa: limit transfer length to 1MB

[PATCH 1/2] hpsa: limit transfer length to 1MB

[Yadan Fan]

The hpsa firmware will bypass the cache for any request larger
than 1MB, so we should cap the request size to avoid any
performance degradation in SLE12-SP2.

This degradation is caused from d2be537c3ba3568acd79cd178327b842e60d035e,
which changed max_sectors_kb to 1280k, but the hardware is able to
work fine with it, so the true fix should be from hpsa driver.

References: bsc#1025461

Signed-off-by: Yadan Fan <ydfan@suse.com>
---
 drivers/scsi/hpsa.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 73daace478cb..b4c0bbea680c 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -952,7 +952,7 @@ static struct scsi_host_template hpsa_driver_template = {
 #endif
 	.sdev_attrs = hpsa_sdev_attrs,
 	.shost_attrs = hpsa_shost_attrs,
-	.max_sectors = 8192,
+	.max_sectors = 1024,
 	.no_write_same = 1,
 };
 
-- 
2.12.3

[PATCH 2/2] smartpqi: limit transfer length to 1MB

[Yadan Fan]

The smartpqi firmware will bypass the cache for any request larger
than 1MB, so we should cap the request size to avoid any
performance degradation on SLE12-SP2

This degradation is caused from d2be537c3ba3568acd79cd178327b842e60d035e,
which changed max_sectors_kb to 1280k, but the hardware is able to
work fine with it, so the true fix should be from smartpqi driver.

Reference: bsc#1025461

Signed-off-by: Yadan Fan <ydfan@suse.com>
---
 drivers/scsi/smartpqi/smartpqi.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/smartpqi/smartpqi.h b/drivers/scsi/smartpqi/smartpqi.h
index b673825f46b5..9513357bd472 100644
--- a/drivers/scsi/smartpqi/smartpqi.h
+++ b/drivers/scsi/smartpqi/smartpqi.h
@@ -630,7 +630,7 @@ struct pqi_encryption_info {
 };
 
 #define PQI_MAX_OUTSTANDING_REQUESTS	((u32)~0)
-#define PQI_MAX_TRANSFER_SIZE		(4 * 1024U * 1024U)
+#define PQI_MAX_TRANSFER_SIZE		(1024U * 1024U)
 
 #define RAID_MAP_MAX_ENTRIES		1024
 
-- 
2.12.3

Re: [PATCH 1/2] hpsa: limit transfer length to 1MB

[Johannes Thumshirn]

On Thu, Jun 22, 2017 at 05:58:44PM +0800, Yadan Fan wrote:
> The hpsa firmware will bypass the cache for any request larger
> than 1MB, so we should cap the request size to avoid any
> performance degradation in SLE12-SP2.
Upstream doesn't care too much about SLES. 

> References: bsc#1025461

and our internal Bugzilla IDs


How about:
The hpsa firmware will bypass the cache for any requests larger than 1MB, so
we shoould cap the request size to avoid any performance regressions in
kernels later than 4.3 

The same applies for Patch 2/2

-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

Re: [PATCH 1/2] hpsa: limit transfer length to 1MB

[Yadan Fan]

Hi Johannes,


On 2017年06月22日 18:06, Johannes Thumshirn wrote:
> On Thu, Jun 22, 2017 at 05:58:44PM +0800, Yadan Fan wrote:
>> The hpsa firmware will bypass the cache for any request larger
>> than 1MB, so we should cap the request size to avoid any
>> performance degradation in SLE12-SP2.
> Upstream doesn't care too much about SLES.
>
>> References: bsc#1025461
> and our internal Bugzilla IDs
>
>
> How about:
> The hpsa firmware will bypass the cache for any requests larger than 1MB, so
> we shoould cap the request size to avoid any performance regressions in
> kernels later than 4.3
>
> The same applies for Patch 2/2

Yes, I agree so, I will resend the modified patches.

Thanks,
Yadan