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From: Neil Horman <nhorman@tuxdriver.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v4 3/5] hash: add fallback to software CRC32 implementation
Date: Tue, 18 Nov 2014 16:36:24 -0500	[thread overview]
Message-ID: <20141118213624.GF32375@hmsreliant.think-freely.org> (raw)
In-Reply-To: <20141118175226.GC5840@bricha3-MOBL3>

On Tue, Nov 18, 2014 at 05:52:27PM +0000, Bruce Richardson wrote:
> On Tue, Nov 18, 2014 at 12:46:19PM -0500, Neil Horman wrote:
> > On Tue, Nov 18, 2014 at 11:13:17PM +0600, Yerden Zhumabekov wrote:
> > > 
> > > 18.11.2014 22:00, Neil Horman пишет:
> > > > On Tue, Nov 18, 2014 at 09:06:35PM +0600, Yerden Zhumabekov wrote:
> > > >> 18.11.2014 20:41, Neil Horman пишет:
> > > >>> On Tue, Nov 18, 2014 at 08:03:40PM +0600, Yerden Zhumabekov wrote:
> > > >>>>  /**
> > > >>>>   * Use single crc32 instruction to perform a hash on a 4 byte value.
> > > >>>> + * Fall back to software crc32 implementation in case SSE4.2 is
> > > >>>> + * not supported
> > > >>>>   *
> > > >>>>   * @param data
> > > >>>>   *   Data to perform hash on.
> > > >>>> @@ -376,11 +413,18 @@ crc32c_2words(uint64_t data, uint32_t init_val)
> > > >>>>  static inline uint32_t
> > > >>>>  rte_hash_crc_4byte(uint32_t data, uint32_t init_val)
> > > >>>>  {
> > > >>>> -	return _mm_crc32_u32(init_val, data);
> > > >>>> +#ifdef RTE_MACHINE_CPUFLAG_SSE4_2
> > > >>>> +	if (likely(crc32_alg == CRC32_SSE42))
> > > >>>> +		return _mm_crc32_u32(init_val, data);
> > > >>>> +#endif
> > > >>> you don't really need these ifdefs here anymore given that you have a
> > > >>> constructor to do the algorithm selection.  In fact you need to remove them, in
> > > >>> the event you build on a system that doesn't support SSE42, but run on a system
> > > >>> that does.
> > > >> Originally, I thought so as well. I wrote the code without these ifdefs,
> > > >> but it didn't compile on my machine which doesn't support SSE4.2. Error
> > > >> was triggered by nmmintrin.h which has a check for respective GCC
> > > >> extension. So I think these ifdefs are indeed required.
> > > >>
> > > > You need to edit the makefile so that the compiler gets passed the option
> > > > -msse42.  That way it will know to emit sse42 instructions. It will also allow
> > > > you to remove the ifdef from the include file
> > > 
> > > In this case, I guess there are two options:
> > > 1) modify all makefiles which use librte_hash
> > > 2) move all function bodies from rte_hash_crc.h to separate module,
> > > leaving prototype definitions there only.
> > > 
> > > Everybody's up for the second option? :)
> > > 
> > Crud, you're right, I didn't think about the header inclusion issue.  Is it
> > worth adding the jump to enable the dynamic hash selection?
> > Neil
> 
> Maybe for cases where SSE4.2 is not currently available, i.e. for generic builds.
> For builds where we have hardware support confirmed at compile time, just use
> the function from the header file.
> Does that make sense?
> 
I'm not certain of that, as I don't think anything can be 'confirmed' at compile
time.  I.e. just because you have sse42 at compile time doesn't guarantee you
have it at run time with a DSO.  If you have these as macros, you need to enable
sse42 whereever you include the file so that the intrinsic works properly.

an alternate option would be to not use the intrinsic, and craft some explicit
__asm__ statement that executes the right sse42 instructions.  That way the asm
is directly emitted, without requiring the -msse42 flag at all, and it will just
work in all the files that call it.

Neil

> /Bruce
> > 
> > > -- 
> > > Sincerely,
> > > 
> > > Yerden Zhumabekov
> > > State Technical Service
> > > Astana, KZ
> > > 
> > > 
> > > 
> 

  reply	other threads:[~2014-11-18 21:26 UTC|newest]

Thread overview: 98+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-03  6:05 [dpdk-dev] [PATCH 0/2] rewritten rte_hash_crc() call Yerden Zhumabekov
2014-09-03  6:05 ` [dpdk-dev] [PATCH 1/2] hash: add new rte_hash_crc_8byte call Yerden Zhumabekov
2014-09-03  6:05 ` [dpdk-dev] [PATCH 2/2] hash: rte_hash_crc uses 8- and 4-byte CRC32 intrinsics Yerden Zhumabekov
2014-11-13 17:33 ` [dpdk-dev] [PATCH 0/2] rewritten rte_hash_crc() call Thomas Monjalon
2014-11-14  0:52   ` Neil Horman
2014-11-14  7:15     ` Yerden Zhumabekov
2014-11-14 11:33       ` Neil Horman
2014-11-14 11:57         ` Yerden Zhumabekov
2014-11-14 13:53           ` Neil Horman
2014-11-14 14:33             ` Thomas Monjalon
2014-11-14 16:43             ` Yerden Zhumabekov
2014-11-14 18:41               ` Neil Horman
2014-11-15 21:45                 ` Yerden Zhumabekov
2014-11-16 17:59 ` [dpdk-dev] [PATCH v2 0/4] rte_hash_crc reworked to be platform-independent Yerden Zhumabekov
2014-11-17 11:31   ` Neil Horman
2014-11-17 11:54     ` Yerden Zhumabekov
2014-11-25 17:05       ` Stephen Hemminger
2014-11-18  3:21   ` [dpdk-dev] [PATCH v3 0/5] " Yerden Zhumabekov
2014-11-18  3:21     ` [dpdk-dev] [PATCH v3 1/5] hash: add software CRC32 implementation Yerden Zhumabekov
2014-11-25 17:34       ` Stephen Hemminger
2014-11-18  3:21     ` [dpdk-dev] [PATCH v3 2/5] hash: add new rte_hash_crc_8byte call Yerden Zhumabekov
2014-11-18  3:21     ` [dpdk-dev] [PATCH v3 3/5] hash: add fallback to software CRC32 implementation Yerden Zhumabekov
2014-11-18  4:56       ` Yerden Zhumabekov
2014-11-18 13:33         ` Neil Horman
2014-11-18 13:37           ` Yerden Zhumabekov
2014-11-18 13:43           ` Thomas Monjalon
2014-11-18  3:21     ` [dpdk-dev] [PATCH v3 4/5] hash: rte_hash_crc() slices data into 8-byte pieces Yerden Zhumabekov
2014-11-18  3:25     ` [dpdk-dev] [PATCH v3 5/5] test: remove redundant compile checks Yerden Zhumabekov
2014-11-16 17:59 ` [dpdk-dev] [PATCH v2 1/4] hash: add software CRC32 implementation Yerden Zhumabekov
2014-11-16 17:59 ` [dpdk-dev] [PATCH v2 2/4] hash: add new rte_hash_crc_8byte call Yerden Zhumabekov
2014-11-16 17:59 ` [dpdk-dev] [PATCH v2 3/4] hash: add fallback to software CRC32 implementation Yerden Zhumabekov
2014-11-17 12:34   ` Ananyev, Konstantin
2014-11-17 12:41     ` Yerden Zhumabekov
2014-11-17 14:06     ` Neil Horman
2014-11-16 17:59 ` [dpdk-dev] [PATCH v2 4/4] hash: rte_hash_crc() slices data into 8-byte pieces Yerden Zhumabekov
2014-11-18 14:03 ` [dpdk-dev] [PATCH v4 0/5] rte_hash_crc reworked to be platform-independent Yerden Zhumabekov
2014-11-18 14:03   ` [dpdk-dev] [PATCH v4 1/5] hash: add software CRC32 implementation Yerden Zhumabekov
2014-11-18 14:03   ` [dpdk-dev] [PATCH v4 2/5] hash: add new rte_hash_crc_8byte call Yerden Zhumabekov
2014-11-18 14:03   ` [dpdk-dev] [PATCH v4 3/5] hash: add fallback to software CRC32 implementation Yerden Zhumabekov
2014-11-18 14:41     ` Neil Horman
2014-11-18 15:06       ` Yerden Zhumabekov
2014-11-18 16:00         ` Neil Horman
2014-11-18 16:04           ` Bruce Richardson
2014-11-18 16:08             ` Bruce Richardson
2014-11-18 16:38             ` Neil Horman
2014-11-18 17:13           ` Yerden Zhumabekov
2014-11-18 17:29             ` Wang, Shawn
2014-11-19  4:07               ` Yerden Zhumabekov
2014-11-18 17:46             ` Neil Horman
2014-11-18 17:52               ` Bruce Richardson
2014-11-18 21:36                 ` Neil Horman [this message]
2014-11-19  3:51                   ` Yerden Zhumabekov
2014-11-19 10:16                   ` Bruce Richardson
2014-11-19 11:34                     ` Neil Horman
2014-11-19 11:38                       ` Bruce Richardson
2014-11-19 11:50                         ` Ananyev, Konstantin
2014-11-19 11:59                           ` Yerden Zhumabekov
2014-11-19 15:05                           ` Neil Horman
2014-11-19 16:51                             ` Ananyev, Konstantin
2014-11-19 11:35                     ` Yerden Zhumabekov
2014-11-19 15:07                       ` Neil Horman
2014-11-20  3:04                         ` Yerden Zhumabekov
2014-11-18 17:58               ` Yerden Zhumabekov
2014-11-18 14:03   ` [dpdk-dev] [PATCH v4 4/5] hash: rte_hash_crc() slices data into 8-byte pieces Yerden Zhumabekov
2014-11-18 14:05   ` [dpdk-dev] [PATCH v4 5/5] test: remove redundant compile checks Yerden Zhumabekov
2014-11-20  5:15 ` [dpdk-dev] [PATCH v5 0/7] rte_hash_crc reworked to be platform-independent Yerden Zhumabekov
2014-11-20  5:16   ` [dpdk-dev] [PATCH v5 1/7] hash: add software CRC32 implementation Yerden Zhumabekov
2014-11-20  5:16   ` [dpdk-dev] [PATCH v5 2/7] hash: add assembly implementation of CRC32 intrinsics Yerden Zhumabekov
2014-11-20  5:16   ` [dpdk-dev] [PATCH v5 3/7] hash: replace built-in functions implementing SSE4.2 Yerden Zhumabekov
2014-11-20  5:16   ` [dpdk-dev] [PATCH v5 4/7] hash: add rte_hash_crc_8byte function Yerden Zhumabekov
2014-11-21 11:22     ` Neil Horman
2014-11-21 11:26       ` Yerden Zhumabekov
2014-11-20  5:17   ` [dpdk-dev] [PATCH v5 6/7] hash: rte_hash_crc() slices data into 8-byte pieces Yerden Zhumabekov
2014-11-20  5:17   ` [dpdk-dev] [PATCH v5 7/7] test: remove redundant compile checks Yerden Zhumabekov
2014-11-20  5:17   ` [dpdk-dev] [PATCH v5 5/7] hash: add fallback to software CRC32 implementation Yerden Zhumabekov
2014-11-27 21:04   ` [dpdk-dev] [PATCH v5 0/7] rte_hash_crc reworked to be platform-independent Thomas Monjalon
2014-11-28  3:28     ` Yerden Zhumabekov
2015-01-29  8:48 ` [dpdk-dev] [PATCH v6 " Yerden Zhumabekov
2015-01-29  8:48   ` [dpdk-dev] [PATCH v6 1/7] hash: add software CRC32 implementation Yerden Zhumabekov
2015-01-29  8:48   ` [dpdk-dev] [PATCH v6 2/7] hash: add assembly implementation of CRC32 intrinsics Yerden Zhumabekov
2015-02-02  5:15     ` Liang, Cunming
2015-02-02  5:34       ` Yerden Zhumabekov
2015-02-02  5:59         ` Liang, Cunming
2015-01-29  8:49   ` [dpdk-dev] [PATCH v6 3/7] hash: replace built-in functions implementing SSE4.2 Yerden Zhumabekov
2015-01-29  8:49   ` [dpdk-dev] [PATCH v6 4/7] hash: add rte_hash_crc_8byte function Yerden Zhumabekov
2015-01-29  8:50   ` [dpdk-dev] [PATCH v6 5/7] hash: add fallback to software CRC32 implementation Yerden Zhumabekov
2015-01-29  8:50   ` [dpdk-dev] [PATCH v6 6/7] hash: rte_hash_crc() slices data into 8-byte pieces Yerden Zhumabekov
2015-01-29  8:50   ` [dpdk-dev] [PATCH v6 7/7] test: remove redundant compile checks Yerden Zhumabekov
2015-02-01 14:13   ` [dpdk-dev] [PATCH v6 0/7] rte_hash_crc reworked to be platform-independent Neil Horman
2015-02-02  3:07     ` Yerden Zhumabekov
2015-02-02  3:31       ` Neil Horman
2015-02-02  5:18         ` [dpdk-dev] HA: " Жумабеков Ерден Мирзагулович
2015-02-02  5:39         ` [dpdk-dev] " Yerden Zhumabekov
2015-02-19 15:21           ` Bruce Richardson
2015-02-23 17:36             ` Thomas Monjalon
2015-02-24  3:00               ` Yerden Zhumabekov
2015-02-24  3:10                 ` Thomas Monjalon
2015-02-24  9:12                   ` Bruce Richardson

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