From: "H. Peter Anvin" <hpa@zytor.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>,
Greg KH <gregkh@linuxfoundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
X86 ML <x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Andi Kleen <ak@linux.intel.com>,
Andrea Arcangeli <aarcange@redhat.com>,
John Stultz <john.stultz@linaro.org>,
Pavel Emelyanov <xemul@parallels.com>,
Cyrill Gorcunov <gorcunov@openvz.org>,
andriy.shevchenko@linux.intel.com,
Martin Runge <Martin.Runge@rohde-schwarz.com>,
Andreas Brief <Andreas.Brief@rohde-schwarz.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 3/3] x86, vdso32: handle 32 bit vDSO larger one page
Date: Thu, 13 Mar 2014 11:21:34 -0700 [thread overview]
Message-ID: <5321F72E.7030109@zytor.com> (raw)
In-Reply-To: <5321F418.1030304@zytor.com>
On 03/13/2014 11:08 AM, H. Peter Anvin wrote:
> On 03/13/2014 10:28 AM, Andy Lutomirski wrote:
>>
>> Does this mean you prefer the relocation approach to the compat vdso
>> removal approach? It seems like Linus is okay with either one.
>>
>
> Actually, thinking about it, removing it is probably better:
>
> a) gets rid of legacy code, making room for unification;
> b) either way enabling compat support (either relocation or disabling
> the vdso) has a performance penalty for *all* processes.
>
> The only way to avoid that is to have a vdso at a fixed addresses across
> all processes, either in the fixmap or in the user area (presumably at
> the very top.)
>
So going back and re-reading all the threads, the consensus was to
remove the compat vdso, but recycling the CONFIG_COMPAT_VDSO
configuration option name for the default-disable option.
It is important that anyone who actually cares about performance unsets
the option.
-hpa
next prev parent reply other threads:[~2014-03-13 18:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-12 22:51 [PATCH 0/3] Improve 32 bit vDSO time Stefani Seibold
2014-03-12 22:51 ` [PATCH 1/3] x86, vdso32: undef CONFIG_OPTIMIZE_INLINING and CONFIG_X86_PPRO_FENCE Stefani Seibold
2014-03-12 22:51 ` [PATCH 2/3] x86, vdso32: remove vsyscall_32.c Stefani Seibold
2014-03-12 22:51 ` [PATCH 3/3] x86, vdso32: handle 32 bit vDSO larger one page Stefani Seibold
2014-03-12 22:58 ` H. Peter Anvin
2014-03-12 22:59 ` Andy Lutomirski
2014-03-13 15:53 ` H. Peter Anvin
2014-03-13 17:28 ` Andy Lutomirski
2014-03-13 18:08 ` H. Peter Anvin
2014-03-13 18:21 ` H. Peter Anvin [this message]
2014-03-13 18:32 ` Andy Lutomirski
2014-03-13 19:01 ` H. Peter Anvin
[not found] ` <CA+55aFyOp6V_tE-sXKVi+=6yVwHQb0sLWSNbk=N7KbhBrx9QhA@mail.gmail.com>
[not found] ` <CA+55aFyCSL==4Ff4JT3uFKN_28mz92ef1L67-4OUGqHZ8HXUhg@mail.gmail.com>
2014-03-13 19:13 ` Andy Lutomirski
[not found] ` <CA+55aFwDn3zA0gEn2r3nJVPWuv-pLYyrj4=8_gt1xFTd2g_Dwg@mail.gmail.com>
2014-03-13 19:33 ` H. Peter Anvin
[not found] ` <CA+55aFxWsm=P5h1o=BNrwkcy2ZadFsVxpegxJ0rskPVcmo_Ljw@mail.gmail.com>
2014-03-13 19:58 ` H. Peter Anvin
2014-03-13 21:00 ` Andi Kleen
2014-03-13 21:04 ` H. Peter Anvin
2014-03-13 21:10 ` Andi Kleen
2014-03-13 21:48 ` Linus Torvalds
2014-03-18 14:22 ` OT: " Hans-Peter Jansen
2014-03-13 19:35 ` Andy Lutomirski
2014-03-12 22:56 ` [PATCH 0/3] Improve 32 bit vDSO time Andy Lutomirski
2014-03-12 23:11 ` stefani
2014-03-13 3:48 ` H. Peter Anvin
2014-03-13 8:11 ` Stefani Seibold
2014-03-13 22:08 ` H. Peter Anvin
2014-03-14 6:24 ` Stefani Seibold
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