[RFC PATCH] ARM: add (experimental) alternative memcpy_{from, to}io() and memset_io()
Hubert Feurstein
h.feurstein at gmail.com
Mon Nov 16 09:57:24 EST 2009
Implement faster memcpy_{to,from}io() and memset_io() by using the
highly optimized mem{cpy,set} implementation instead of sequential
8bit read/write accesses. This gives significantly higher throughput
accessing big iomem-regions.
Signed-off-by: Hubert Feurstein <h.feurstein at gmail.com>
---
Hi Russell,
would such a patch be acceptable, since it would not break existing users?
Would be great if some people from the community could test it and post their
experience.
Regards
Hubert
arch/arm/Kconfig | 12 ++++++++++++
arch/arm/include/asm/io.h | 6 ++++++
2 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 1c4119c..2723948 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1221,6 +1221,18 @@ config UACCESS_WITH_MEMCPY
However, if the CPU data cache is using a write-allocate mode,
this option is unlikely to provide any performance gain.
+config OPTIMIZED_IOMEM_MEMCPY
+ bool "Use kernel memcpy() for memcpy_{from,to}io() (EXPERIMENTAL)"
+ depends on EXPERIMENTAL
+ help
+ Implement faster memcpy_{to,from}io() and memset_io() by using the
+ highly optimized mem{cpy,set} implementation instead of sequential
+ 8bit read/write accesses. This gives significantly higher throughput
+ accessing big iomem-regions.
+
+ This might not work on all machines in case they have problems accessing
+ the iomem-space word-by-word.
+
endmenu
menu "Boot options"
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index d2a59cf..b37e057 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -195,9 +195,15 @@ extern void _memset_io(volatile void __iomem *, int, size_t);
#define writesw(p,d,l) __raw_writesw(__mem_pci(p),d,l)
#define writesl(p,d,l) __raw_writesl(__mem_pci(p),d,l)
+#ifdef CONFIG_OPTIMIZED_IOMEM_MEMCPY
+#define memset_io(c,v,l) memset(__mem_pci(c),(v),(l))
+#define memcpy_fromio(a,c,l) memcpy((a),__mem_pci(c),(l))
+#define memcpy_toio(c,a,l) memcpy(__mem_pci(c),(a),(l))
+#else
#define memset_io(c,v,l) _memset_io(__mem_pci(c),(v),(l))
#define memcpy_fromio(a,c,l) _memcpy_fromio((a),__mem_pci(c),(l))
#define memcpy_toio(c,a,l) _memcpy_toio(__mem_pci(c),(a),(l))
+#endif
#elif !defined(readb)
--
1.6.4.4
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