From: Dave Hansen <dave.hansen@intel.com>
To: Rong Tao <rtoax@foxmail.com>, tglx@linutronix.de
Cc: Rong Tao <rongtao@cestc.cn>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/vdso: Use non-serializing instruction rdtsc
Date: Tue, 16 May 2023 07:12:34 -0700 [thread overview]
Message-ID: <56ea846e-bce8-2508-e485-1dada8c39643@intel.com> (raw)
In-Reply-To: <tencent_4DC4468312A1CB2CA34B0215FAD797D11F07@qq.com>
On 5/15/23 23:52, Rong Tao wrote:
> Replacing rdtscp or 'lfence;rdtsc' with the non-serializable instruction
> rdtsc can achieve a 40% performance improvement with only a small loss of
> precision.
I think the minimum that can be done in a changelog like this is to
figure out _why_ a RDTSCP was in use. There are a ton of things that
can make the kernel go faster, but not all of them are a good idea.
I assume that the folks that wrote this had good reason for not using
plain RSTSC. What were those reasons?
next prev parent reply other threads:[~2023-05-16 14:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-16 6:52 Rong Tao
2023-05-16 14:12 ` Dave Hansen [this message]
2023-05-16 17:57 ` H. Peter Anvin
2023-05-16 20:39 ` Thomas Gleixner
2023-05-16 14:20 ` Thomas Gleixner
2023-05-16 21:53 ` Andy Lutomirski
2023-05-17 0:41 ` Rong Tao
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