From: Richard Henderson <richard.henderson@linaro.org>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: qemu-devel@nongnu.org, jmario@redhat.com
Subject: Re: Prefetches in buffer_zero_*
Date: Thu, 22 Jul 2021 08:53:17 -1000 [thread overview]
Message-ID: <092f9b8b-4a14-d059-49be-010b760828aa@linaro.org> (raw)
In-Reply-To: <YPlCJpMIOb2Umc+Z@work-vm>
On 7/22/21 12:02 AM, Dr. David Alan Gilbert wrote:
> Hi Richard,
> I think you were the last person to fiddle with the prefetching
> in buffer_zero_avx2 and friends; Joe (cc'd) wondered if explicit
> prefetching still made sense on modern CPUs, and that their hardware
> generally figures stuff out better on simple increments.
>
> What was your thinking on this, and did you actually measure
> any improvement?
Ah, well, that was 5 years ago so I have no particular memory of this. It wouldn't
surprise me if you can't measure any improvement on modern hardware.
Do you now measure an improvement with the prefetches gone?
r~
next prev parent reply other threads:[~2021-07-22 18:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-22 10:02 Prefetches in buffer_zero_* Dr. David Alan Gilbert
2021-07-22 18:53 ` Richard Henderson [this message]
2021-07-22 19:13 ` Dr. David Alan Gilbert
2021-07-24 1:43 ` Joe Mario
2021-07-26 8:47 ` Dr. David Alan Gilbert
2021-07-26 11:31 ` Philippe Mathieu-Daudé
2021-07-26 12:07 ` Dr. David Alan Gilbert
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