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From: Stephen Hemminger <stephen@networkplumber.org>
To: "Varghese, Vipin" <vipin.varghese@amd.com>
Cc: ferruh.yigit@amd.com, bruce.richardson@intel.com,
	konstantin.v.ananyev@yandex.ru, aman.deep.singh@intel.com,
	dev@dpdk.org
Subject: Re: [PATCH v2 1/3] app/testpmd: add register keyword
Date: Tue, 27 Aug 2024 10:39:37 -0700	[thread overview]
Message-ID: <20240827103924.1d1d2711@hermes.local> (raw)
In-Reply-To: <f68c361b-0f3f-4ec4-ab78-79b3ac921aee@amd.com>

On Tue, 27 Aug 2024 21:02:00 +0530
"Varghese, Vipin" <vipin.varghese@amd.com> wrote:

> On 8/21/2024 8:25 PM, Stephen Hemminger wrote:
> > Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
> >
> >
> > On Wed, 21 Aug 2024 20:08:55 +0530
> > Vipin Varghese<vipin.varghese@amd.com>  wrote:
> >  
> >> diff --git a/app/test-pmd/macswap_sse.h b/app/test-pmd/macswap_sse.h
> >> index 223f87a539..29088843b7 100644
> >> --- a/app/test-pmd/macswap_sse.h
> >> +++ b/app/test-pmd/macswap_sse.h
> >> @@ -16,13 +16,13 @@ do_macswap(struct rte_mbuf *pkts[], uint16_t nb,
> >>        uint64_t ol_flags;
> >>        int i;
> >>        int r;
> >> -     __m128i addr0, addr1, addr2, addr3;
> >> +     register __m128i addr0, addr1, addr2, addr3;  
> > Some compilers treat register as a no-op. Are you sure? Did you check with godbolt.  
> 
> Thank you Stephen, I have tested the code changes on Linux using GCC and 
> Clang compiler.
> 
> In both cases in Linux environment, we have seen the the values loaded 
> onto register `xmm`.
> 
> ```
> registerconst__m128i shfl_msk = _mm_set_epi8(15, 14, 13, 12, 5, 4, 3, 2, 
> 1, 0, 11, 10, 9, 8, 7, 6);
> vmovdqaxmm0, xmmwordptr[rip+ .LCPI0_0]
> 
> ```
> 
> Both cases we have performance improvement.
> 
> 
> Can you please help us understand if we have missed out something?

Ok, not sure why compiler would not decide to already use a register here?

  reply	other threads:[~2024-08-27 18:00 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-07-16  6:37 [PATCH] app/testpmd: improve sse based macswap Vipin Varghese
2024-07-23 16:45 ` Ferruh Yigit
2024-07-23 17:12   ` Bruce Richardson
2024-07-25 12:47     ` Varghese, Vipin
2024-07-25 12:52       ` Bruce Richardson
2024-08-21 14:38 ` [PATCH v2 0/3] " Vipin Varghese
2024-08-21 14:38   ` [PATCH v2 1/3] app/testpmd: add register keyword Vipin Varghese
2024-08-21 14:55     ` Stephen Hemminger
2024-08-27 15:32       ` Varghese, Vipin
2024-08-27 17:39         ` Stephen Hemminger [this message]
2024-08-29  8:14           ` Varghese, Vipin
2024-09-03 11:52           ` Konstantin Ananyev
2024-09-06 13:02             ` Varghese, Vipin
2024-10-04  5:04               ` Ferruh Yigit
2024-08-21 14:38   ` [PATCH v2 2/3] app/testpmd: move offload update Vipin Varghese
2024-08-21 14:38   ` [PATCH v2 3/3] app/testpmd: interleave SSE SIMD Vipin Varghese
2024-10-04  5:08   ` [PATCH v2 0/3] app/testpmd: improve sse based macswap Ferruh Yigit
2024-10-08  1:12     ` Ferruh Yigit

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