Edward, Thanks for your contribution. Please file a JIRA ticket at http://issues.apache.org/jira/browse/HADOOP and upload your patch there. Other reviewers/committers can take it from there and provide feedback. For more instructions, you can see http://wiki.apache.org/hadoop/HowToContribute.
HTH
+Vinod
On Jun 25, 2014, at 2:03 AM, Edward Nevill <edward.nev...@linaro.org> wrote:
> Hi,
>
> I would like to add support for hardware crc for ARM's new 64 bit
> architecture, aarch64.
>
> I would be grateful if some committer could help me though the process of
> getting this change pushed into the trunk.
>
> I have prepared an initial patch below.
>
> The patch is completely conditionalized on __arch64__
>
> For the moment I have only done the non pipelined version as the hw I have
> only has 1 crc execute unit.
>
> Some initial benchmarks on terasort give
>
> sw crc: 107 sec
> hw crc: 103 sec
>
> The performance improvement is quite small, but this is limited by the fact
> that I am using early stage hw which is not performant.
>
> I have also built it on x86 and I think the change is fairly safe for other
> architectures because post conditionalization the src is identical on other
> architectures.
>
> Thanks for you help,
> Ed.
>
>
> --- CUT HERE ---
> Index:
> hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/util/bulk_crc32.c
> ===================================================================
> ---
> hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/util/bulk_crc32.c
> (revision 1605031)
> +++
> hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/util/bulk_crc32.c
> (working copy)
> @@ -38,7 +38,7 @@
> #include "bulk_crc32.h"
> #include "gcc_optimizations.h"
>
> -#if (!defined(__FreeBSD__) && !defined(WINDOWS))
> +#if (!defined(__FreeBSD__) && !defined(WINDOWS)) && !defined(__aarch64__)
> #define USE_PIPELINED
> #endif
>
> @@ -672,8 +672,61 @@
>
> # endif // 64-bit vs 32-bit
>
> -#else // end x86 architecture
> +#elif defined(__aarch64__) // end x86 architecture
>
> +#include <sys/auxv.h>
> +#include <asm/hwcap.h>
> +
> +#ifndef HWCAP_CRC32
> +#define HWCAP_CRC32 (1<<7)
> +#endif
> +
> +/**
> + * On library load, determine what sort of crc we are going to do
> + * and set cached_cpu_supports_crc32 appropriately.
> + */
> +void __attribute__ ((constructor)) init_cpu_support_flag(void) {
> + unsigned long auxv = getauxval(AT_HWCAP);
> + cached_cpu_supports_crc32 = auxv & HWCAP_CRC32;
> +}
> +
> +#define CRC32X(crc,value) asm("crc32cx %w[c], %w[c], %x[v]" : [c]"+r"(crc) :
> [v]"r"(value))
> +#define CRC32W(crc,value) asm("crc32cw %w[c], %w[c], %w[v]" : [c]"+r"(crc) :
> [v]"r"(value))
> +#define CRC32H(crc,value) asm("crc32ch %w[c], %w[c], %w[v]" : [c]"+r"(crc) :
> [v]"r"(value))
> +#define CRC32B(crc,value) asm("crc32cb %w[c], %w[c], %w[v]" : [c]"+r"(crc) :
> [v]"r"(value))
> +
> +/**
> + * Hardware-accelerated CRC32C calculation using the 64-bit instructions.
> + */
> +static uint32_t crc32c_hardware(uint32_t crc, const uint8_t* p_buf, size_t
> length) {
> + int64_t len = length;
> + asm(".cpu generic+crc"); // Allow crc instructions in asm
> + if ((len -= sizeof(uint64_t)) >= 0) {
> + do {
> + CRC32X(crc, *(uint64_t*)p_buf);
> + p_buf += sizeof(uint64_t);
> + } while ((len -= sizeof(uint64_t)) >= 0);
> + }
> +
> + // The following is more efficient than the straight loop
> + if (len & sizeof(uint32_t)) {
> + CRC32W(crc, *(uint32_t*)p_buf);
> + p_buf += sizeof(uint32_t);
> + }
> + if (len & sizeof(uint16_t)) {
> + CRC32H(crc, *(uint16_t*)p_buf);
> + p_buf += sizeof(uint16_t);
> + }
> + if (len & sizeof(uint8_t)) {
> + CRC32B(crc, *p_buf);
> + p_buf++;
> + }
> +
> + return crc;
> +}
> +
> +#else
> +
> static uint32_t crc32c_hardware(uint32_t crc, const uint8_t* data, size_t
> length) {
> // never called!
> assert(0 && "hardware crc called on an unsupported platform");
> --- CUT HERE ---
>
>
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