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[PATCH v2 1/2] hpsa: limit transfer length to 1MB

Started byYadan Fan <ydfan@suse.com>
First post2017-06-23 11:50 +0200
Last post2017-06-26 19:40 +0200
Articles 3 — 3 participants

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  [PATCH v2 1/2] hpsa: limit transfer length to 1MB Yadan Fan <ydfan@suse.com> - 2017-06-23 11:50 +0200
    Re: [PATCH v2 1/2] hpsa: limit transfer length to 1MB Johannes Thumshirn <jthumshirn@suse.de> - 2017-06-23 15:10 +0200
    Re: [PATCH v2 1/2] hpsa: limit transfer length to 1MB "Martin K. Petersen" <martin.petersen@oracle.com> - 2017-06-26 19:40 +0200

#1673444 — [PATCH v2 1/2] hpsa: limit transfer length to 1MB

FromYadan Fan <ydfan@suse.com>
Date2017-06-23 11:50 +0200
Subject[PATCH v2 1/2] hpsa: limit transfer length to 1MB
Message-ID<tVtnX-rz-3@gated-at.bofh.it>
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 kernels later than v4.3

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.

Signed-off-by: Yadan Fan <ydfan@suse.com>
---

Changes: 
 Reduced SUSE distribution info and internal bug id reference.

 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

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#1673540

FromJohannes Thumshirn <jthumshirn@suse.de>
Date2017-06-23 15:10 +0200
Message-ID<tVwvw-2AS-29@gated-at.bofh.it>
In reply to#1673444
On Fri, Jun 23, 2017 at 05:40:05PM +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 kernels later than v4.3
> 
> 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.
> 
> Signed-off-by: Yadan Fan <ydfan@suse.com>
> ---

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
-- 
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

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#1674969

From"Martin K. Petersen" <martin.petersen@oracle.com>
Date2017-06-26 19:40 +0200
Message-ID<tWG9s-5iW-27@gated-at.bofh.it>
In reply to#1673444
Don,

> 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 kernels later than v4.3

I assume you guys are OK with this change?

-- 
Martin K. Petersen	Oracle Linux Engineering

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