From a426dcff62d959a840d2208bb1a6ca31c00d49ab Mon Sep 17 00:00:00 2001
From: Yadan Fan <ydfan@suse.com>
Date: Wed, 3 May 2017 16:50:02 +0800
Subject: [PATCH] smartpqi: limit transfer length to 1MB
Git-commit: eeee4107546ef24c739d72645899e50fa693e9ff
Patch-mainline: v4.13-rc3
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 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 smartpqi driver.
References: bsc#1025461
Signed-off-by: Yadan Fan <ydfan@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
---
drivers/scsi/smartpqi/smartpqi.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/scsi/smartpqi/smartpqi.h
+++ b/drivers/scsi/smartpqi/smartpqi.h
@@ -690,7 +690,7 @@ struct pqi_config_table_heartbeat {
#define PQI_MAX_OUTSTANDING_REQUESTS ((u32)~0)
#define PQI_MAX_OUTSTANDING_REQUESTS_KDUMP 32
-#define PQI_MAX_TRANSFER_SIZE (4 * 1024U * 1024U)
+#define PQI_MAX_TRANSFER_SIZE (1024U * 1024U)
#define PQI_MAX_TRANSFER_SIZE_KDUMP (512 * 1024U)
#define RAID_MAP_MAX_ENTRIES 1024