From: Will Deacon <will@kernel.org>
To: "Lixin (Victor, Kirin)" <victor.lixin@hisilicon.com>
Cc: "fujun \(F\)" <oliver.fu@hisilicon.com>,
Wuxuecheng <wuxuecheng@hisilicon.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: Please help to confirm the risk if using TPIDRRO_EL0 to save CPU number, thanks.
Date: Mon, 1 Jun 2020 08:03:12 +0100 [thread overview]
Message-ID: <20200601070311.GA8601@willie-the-truck> (raw)
In-Reply-To: <1D289F1E6D91D2489524BBB0B8880A7DA1A39219@dggeml509-mbx.china.huawei.com>
On Fri, May 29, 2020 at 09:03:37AM +0000, Lixin (Victor, Kirin) wrote:
> Intel optimized getcpu syscall on Linux/Android system by using vDSO, but
> ARM doesn't do any optimizations for getcpu syscall.
>
> In Apple open source, TPIDRRO_EL0/TPIDRURO is used to save the CPU number,
> [1]https://opensource.apple.com/source/xnu/xnu-4570.1.46/osfmk/arm/cswitch.s.auto.html
>
> Is there any risk if using TPIDRRO_EL0/TPIDRURO to implement
> the vDSO for getcpu? Is there any possible to break any ARM ABI? Can you
> help us to confirm the considerations?
Do you have a use-case for high-performance getcpu() that isn't better
suited to rseq()?
Will
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next parent reply other threads:[~2020-06-01 7:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1D289F1E6D91D2489524BBB0B8880A7DA1A39219@dggeml509-mbx.china.huawei.com>
2020-06-01 7:03 ` Will Deacon [this message]
2020-06-05 12:10 ` Please help to confirm the risk if using TPIDRRO_EL0 to save CPU number, thanks Mark Brown
2020-06-05 12:33 ` Will Deacon
2020-06-05 12:58 ` Robin Murphy
2020-06-05 13:02 ` Will Deacon
2020-06-05 13:23 ` Robin Murphy
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=20200601070311.GA8601@willie-the-truck \
--to=will@kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=oliver.fu@hisilicon.com \
--cc=victor.lixin@hisilicon.com \
--cc=wuxuecheng@hisilicon.com \
/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