From: Richard Henderson <richard.henderson@linaro.org>
To: Alexander Monakov <amonakov@ispras.ru>, qemu-devel@nongnu.org
Cc: Mikhail Romanov <mmromanov@ispras.ru>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v3 3/6] util/bufferiszero: remove AVX512 variant
Date: Wed, 7 Feb 2024 08:28:48 +1000 [thread overview]
Message-ID: <2263455d-7f03-48fb-ab0b-f2a6100edcc8@linaro.org> (raw)
In-Reply-To: <20240206204809.9859-4-amonakov@ispras.ru>
On 2/7/24 06:48, Alexander Monakov wrote:
> Thanks to early checks in the inline buffer_is_zero wrapper, the SIMD
> routines are invoked much more rarely in normal use when most buffers
> are non-zero. This makes use of AVX512 unprofitable, as it incurs extra
> frequency and voltage transition periods during which the CPU operates
> at reduced performance, as described in
> https://travisdowns.github.io/blog/2020/01/17/avxfreq1.html
>
> Signed-off-by: Mikhail Romanov<mmromanov@ispras.ru>
> Signed-off-by: Alexander Monakov<amonakov@ispras.ru>
> ---
> util/bufferiszero.c | 36 ++----------------------------------
> 1 file changed, 2 insertions(+), 34 deletions(-)
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Although I think this patch should be ordered second.
r~
next prev parent reply other threads:[~2024-02-06 22:29 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-06 20:48 [PATCH v3 0/6] Optimize buffer_is_zero Alexander Monakov
2024-02-06 20:48 ` [PATCH v3 1/6] util/bufferiszero: remove SSE4.1 variant Alexander Monakov
2024-02-06 22:24 ` Richard Henderson
2024-02-06 20:48 ` [PATCH v3 2/6] util/bufferiszero: introduce an inline wrapper Alexander Monakov
2024-02-06 22:44 ` Richard Henderson
2024-02-07 7:13 ` Alexander Monakov
2024-02-08 20:07 ` Richard Henderson
2024-02-06 20:48 ` [PATCH v3 3/6] util/bufferiszero: remove AVX512 variant Alexander Monakov
2024-02-06 22:28 ` Richard Henderson [this message]
2024-02-06 23:56 ` Elena Ufimtseva
2024-02-07 6:29 ` Alexander Monakov
2024-02-07 10:38 ` Joao Martins
2024-02-06 20:48 ` [PATCH v3 4/6] util/bufferiszero: remove useless prefetches Alexander Monakov
2024-02-06 22:29 ` Richard Henderson
2024-02-06 20:48 ` [PATCH v3 5/6] util/bufferiszero: optimize SSE2 and AVX2 variants Alexander Monakov
2024-02-06 23:10 ` Richard Henderson
2024-02-06 20:48 ` [PATCH v3 6/6] util/bufferiszero: improve scalar variant Alexander Monakov
2024-02-06 22:34 ` Richard Henderson
2024-02-06 22:46 ` Richard Henderson
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