From: JackieLiu <liuyun01@kylinos.cn>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Andrew Pinski <apinski@cavium.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: Built a neon version copy_page/clear_page is correct?
Date: Wed, 12 Dec 2018 15:32:17 +0800 [thread overview]
Message-ID: <370722B9-5CAE-4420-9126-3DF805BC115B@kylinos.cn> (raw)
In-Reply-To: <CAKv+Gu-OWVd_oq-Zb49Kgsswr99oZ5pUOoTN5pkYPFmRDDWoOA@mail.gmail.com>
Yes. I have a bottleneck, maybe it’s not copy_page’s. but
during the debugging process, this function has a very high
CPU utilization.
The test program is UnixBench’s src/spawn.c, with a while to
fork process. The only variable for test is PAGE_SIZE, one is
4k PAGE_SIZE, next is 64k PAGE_SIZE.
result for "perf top":
4k | 13% CPU copy_page
64k | 48% CPU copy_page
This is why I want to optimize this function. Maybe bottleneck
is not here?
> 在 2018年12月12日，15:18，Ard Biesheuvel <ard.biesheuvel@linaro.org> 写道：
>
> As for copy_page(), please describe a use case where it is a
> bottleneck, and reason about how much you could improve performance in
> that case by improving the speed of copy_page() itself. Otherwise,
> we're just adding NEON routines for the sake if it, which is a bad
> idea imo.
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next prev parent reply other threads:[~2018-12-12 7:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-12 6:01 Built a neon version copy_page/clear_page is correct? JackieLiu
2018-12-12 7:18 ` Ard Biesheuvel
2018-12-12 7:32 ` JackieLiu [this message]
2018-12-12 11:45 ` Robin Murphy
2018-12-12 11:58 ` JackieLiu
2018-12-12 12:21 ` Russell King - ARM Linux
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