linux-kernel - [PATCH 13/20] drivers/block/pmem: Map NVDIMM in Write-Through mode

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Date:	Thu,  4 Jun 2015 18:55:21 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 13/20] drivers/block/pmem: Map NVDIMM in Write-Through mode

From: Toshi Kani <toshi.kani@...com>

The pmem driver maps NVDIMM uncacheable so that we don't lose data which
hasn't reached non-volatile storage in the case of a crash. Change this
to Write-Through mode which provides uncached writes but cached reads,
thus improving read performance.

Signed-off-by: Toshi Kani <toshi.kani@...com>
Acked-by: Dan Williams <dan.j.williams@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: arnd@...db.de
Cc: Elliott@...com
Cc: hch@....de
Cc: hmh@....eng.br
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: jgross@...e.com
Cc: konrad.wilk@...cle.com
Cc: linux-mm <linux-mm@...ck.org>
Cc: linux-nvdimm@...ts.01.org
Cc: Luis R. Rodriguez <mcgrof@...e.com>
Cc: stefan.bader@...onical.com
Cc: x86-ml <x86@...nel.org>
Cc: yigal@...xistor.com
Link: http://lkml.kernel.org/r/1432739944-22633-13-git-send-email-toshi.kani@hp.com
Signed-off-by: Borislav Petkov <bp@...e.de>
---
 drivers/block/pmem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/block/pmem.c b/drivers/block/pmem.c
index eabf4a8d0085..095dfaadcaa5 100644
--- a/drivers/block/pmem.c
+++ b/drivers/block/pmem.c
@@ -139,11 +139,11 @@ static struct pmem_device *pmem_alloc(struct device *dev, struct resource *res)
 	}
 
 	/*
-	 * Map the memory as non-cachable, as we can't write back the contents
+	 * Map the memory as write-through, as we can't write back the contents
 	 * of the CPU caches in case of a crash.
 	 */
 	err = -ENOMEM;
-	pmem->virt_addr = ioremap_nocache(pmem->phys_addr, pmem->size);
+	pmem->virt_addr = ioremap_wt(pmem->phys_addr, pmem->size);
 	if (!pmem->virt_addr)
 		goto out_release_region;
 
-- 
2.3.5

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