From: Andi Kleen <ak@linux.intel.com>
To: Samuel Neves <sneves@dei.uc.pt>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/usercopy: speed up 64-bit __clear_user() with stos{b,q}
Date: Sun, 23 May 2021 20:43:54 -0700 [thread overview]
Message-ID: <761811e5-d693-ed33-c6ba-ce8cf2e5046c@linux.intel.com> (raw)
In-Reply-To: <20210523180423.108087-1-sneves@dei.uc.pt>
On 5/23/2021 11:04 AM, Samuel Neves wrote:
> The
> This change is noticeable from userspace. That is in fact how I spotted it; in
> a hashing benchmark that read from /dev/zero, around 10-15% of the CPU time
> was spent in __clear_user. After this patch, on a Skylake CPU, these are the
> before/after figures:
>
> $ dd if=/dev/zero of=/dev/null bs=1024k status=progress
> 94402248704 bytes (94 GB, 88 GiB) copied, 6 s, 15.7 GB/s
The question is of course if this actually represents any real workload.
-Andi
next prev parent reply other threads:[~2021-05-24 3:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-23 18:04 [PATCH] x86/usercopy: speed up 64-bit __clear_user() with stos{b,q} Samuel Neves
2021-05-23 19:03 ` Borislav Petkov
2021-05-24 3:43 ` Andi Kleen [this message]
2021-05-24 8:29 ` David Laight
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