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Commit bc4d0f61 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'ovs_hash' 



Francesco Fusco says:

====================
ovs: introduce arch-specific fast hashing improvements

From: Daniel Borkmann <dborkman@redhat.com>

We are introducing a fast hash function (see patch1) that can be
used in the context of OpenVSwitch to reduce the hashing footprint
(patch2). For details, please see individual patches!

v1->v2:
 - Make hash generic and place it under lib
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 89e47d3b 500f8087

arch/x86/include/asm/hash.h

0 → 100644
+7 −0
Original line number Diff line number Diff line 
#ifndef _ASM_X86_HASH_H

#define _ASM_X86_HASH_H



struct fast_hash_ops;

extern void setup_arch_fast_hash(struct fast_hash_ops *ops);



#endif /* _ASM_X86_HASH_H */

arch/x86/lib/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -24,7 +24,7 @@ lib-$(CONFIG_SMP) += rwlock.o 
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o

lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o



obj-y += msr.o msr-reg.o msr-reg-export.o

obj-y += msr.o msr-reg.o msr-reg-export.o hash.o



ifeq ($(CONFIG_X86_32),y)

        obj-y += atomic64_32.o

arch/x86/lib/hash.c

0 → 100644
+88 −0
Original line number Diff line number Diff line 
/*

 * Some portions derived from code covered by the following notice:

 *

 * Copyright (c) 2010-2013 Intel Corporation. All rights reserved.

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 *   * Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 *   * Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in

 *     the documentation and/or other materials provided with the

 *     distribution.

 *   * Neither the name of Intel Corporation nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */



#include <linux/hash.h>



#include <asm/processor.h>

#include <asm/cpufeature.h>

#include <asm/hash.h>



static inline u32 crc32_u32(u32 crc, u32 val)

{

	asm ("crc32l %1,%0\n" : "+r" (crc) : "rm" (val));

	return crc;

}



static u32 intel_crc4_2_hash(const void *data, u32 len, u32 seed)

{

	const u32 *p32 = (const u32 *) data;

	u32 i, tmp = 0;



	for (i = 0; i < len / 4; i++)

		seed = crc32_u32(*p32++, seed);



	switch (3 - (len & 0x03)) {

	case 0:

		tmp |= *((const u8 *) p32 + 2) << 16;

		/* fallthrough */

	case 1:

		tmp |= *((const u8 *) p32 + 1) << 8;

		/* fallthrough */

	case 2:

		tmp |= *((const u8 *) p32);

		seed = crc32_u32(tmp, seed);

	default:

		break;

	}



	return seed;

}



static u32 intel_crc4_2_hash2(const u32 *data, u32 len, u32 seed)

{

	const u32 *p32 = (const u32 *) data;

	u32 i;



	for (i = 0; i < len; i++)

		seed = crc32_u32(*p32++, seed);



	return seed;

}



void setup_arch_fast_hash(struct fast_hash_ops *ops)

{

	if (cpu_has_xmm4_2) {

		ops->hash  = intel_crc4_2_hash;

		ops->hash2 = intel_crc4_2_hash2;

	}

}

include/asm-generic/hash.h

0 → 100644
+9 −0
Original line number Diff line number Diff line 
#ifndef __ASM_GENERIC_HASH_H

#define __ASM_GENERIC_HASH_H



struct arch_hash_ops;

static inline void setup_arch_fast_hash(struct arch_hash_ops *ops)

{

}



#endif /* __ASM_GENERIC_HASH_H */

include/linux/hash.h

+36 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
 */



#include <asm/types.h>

#include <asm/hash.h>

#include <linux/compiler.h>



/* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
@@ -78,4 +79,39 @@ static inline u32 hash32_ptr(const void *ptr) 
#endif

	return (u32)val;

}



struct fast_hash_ops {

	u32 (*hash)(const void *data, u32 len, u32 seed);

	u32 (*hash2)(const u32 *data, u32 len, u32 seed);

};



/**

 *	arch_fast_hash - Caclulates a hash over a given buffer that can have

 *			 arbitrary size. This function will eventually use an

 *			 architecture-optimized hashing implementation if

 *			 available, and trades off distribution for speed.

 *

 *	@data: buffer to hash

 *	@len: length of buffer in bytes

 *	@seed: start seed

 *

 *	Returns 32bit hash.

 */

extern u32 arch_fast_hash(const void *data, u32 len, u32 seed);



/**

 *	arch_fast_hash2 - Caclulates a hash over a given buffer that has a

 *			  size that is of a multiple of 32bit words. This

 *			  function will eventually use an architecture-

 *			  optimized hashing implementation if available,

 *			  and trades off distribution for speed.

 *

 *	@data: buffer to hash (must be 32bit padded)

 *	@len: number of 32bit words

 *	@seed: start seed

 *

 *	Returns 32bit hash.

 */

extern u32 arch_fast_hash2(const u32 *data, u32 len, u32 seed);



#endif /* _LINUX_HASH_H */