From: Andi Kleen <ak@linux.intel.com>
To: Martin Leitner-Ankerl <martin.ankerl@gmail.com>
Cc: Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Youling Tang <youling.tang@linux.dev>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>,
llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
Youling Tang <tangyouling@kylinos.cn>,
Nikolay Borisov <nik.borisov@suse.com>
Subject: Re: [PATCH] x86/cpu: Use prefetcht0 for prefetch() on 64-bit
Date: Tue, 3 Nov 2026 17:41:35 -0800 [thread overview]
Message-ID: <auqNT3yNeA1ujmW3@tassilo> (raw)
In-Reply-To: <20261103060658.696994-1-martin.ankerl@gmail.com>
> +#ifdef CONFIG_X86_64
> +/*
> + * Every x86-64 CPU has prefetcht0. Not __builtin_prefetch(): the kernel
> + * builds with -mno-sse, and clang then drops the builtin without a warning.
> + */
> +static inline void prefetch(const void *x)
> +{
> + asm("prefetcht0 %0" : : "m" (*(const char *)x));
> +}
> +#else
One thing you should check if the inline assembly pessimizes the code on
gcc. Normally builtins can be better optimized. Or keep using the builtin
on gcc to be safe.
-Andi
prev parent reply other threads:[~2026-11-04 1:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-03 6:06 Martin Leitner-Ankerl
2026-11-03 17:23 ` Nick Desaulniers
2026-11-04 1:41 ` Andi Kleen [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=auqNT3yNeA1ujmW3@tassilo \
--to=ak@linux.intel.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=justinstitt@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=llvm@lists.linux.dev \
--cc=martin.ankerl@gmail.com \
--cc=mingo@redhat.com \
--cc=morbo@google.com \
--cc=nathan@kernel.org \
--cc=ndesaulniers@google.com \
--cc=nik.borisov@suse.com \
--cc=peterz@infradead.org \
--cc=tangyouling@kylinos.cn \
--cc=tglx@kernel.org \
--cc=x86@kernel.org \
--cc=youling.tang@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®