lkml.org 
[lkml]   [2019]   [Jun]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v7 00/25] Unify vDSOs across more architectures
    From
    Date
    Hi Thomas,

    On 24/06/2019 01:34, Thomas Gleixner wrote:
    > Vincenzo,
    >
    > On Fri, 21 Jun 2019, Vincenzo Frascino wrote:
    >> vDSO (virtual dynamic shared object) is a mechanism that the Linux
    >> kernel provides as an alternative to system calls to reduce where
    >> possible the costs in terms of cycles.
    >> This is possible because certain syscalls like gettimeofday() do
    >> not write any data and return one or more values that are stored
    >> in the kernel, which makes relatively safe calling them directly
    >> as a library function.
    >>
    >> Even if the mechanism is pretty much standard, every architecture
    >> in the last few years ended up implementing their own vDSO library
    >> in the architectural code.
    >
    > ....
    >
    >> This implementation contains the portings to the common library for: arm64,
    >> compat mode for arm64, arm, mips, x86_64, x32, compat mode for x86_64 and
    >> i386.
    >
    > I picked up the core implementation and the ARM64 and x86 conversion. I did
    > some refinements in several places, coding style, naming conventions,
    > comments and changelogs including subject prefixes. Please double check!
    >

    I tested your changes and they seem OK
    (git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/vdso).

    ...
    > As you can see from the commit dates, this has soaked for some time in a
    > WIP branch and I did extensive regression testing. So far so good.
    >
    > Thanks a lot for going through several iterations. It's a very much
    > appreciated effort!
    >

    It has been a lot of fun and I learned many many things about the vDSOs and the
    kernel that I did not know before. Thanks to you for your patience and guidance.

    > Especially with the upcoming time namespaces this will avoid a lot of
    > duplicated and pointlessly different horrors all over the architecture
    > space. Any architecture which wants to gain that support needs to convert
    > to the generic VDSO first.
    >
    > As you have become the dude who knows almost everything about VDSO
    > including all the nasty pitfalls, I propose the patch below.
    >

    Thanks for this, it means a lot to me.

    > Thanks,
    >
    > tglx
    >
    > 8<------------
    > Subject: MAINTAINERS: Add entry for the generic VDSO library
    > From: Thomas Gleixner <tglx@linutronix.de>
    > Date: Mon, 24 Jun 2019 02:03:50 +0200
    >
    > Asign the following folks in alphabetic order:
    >
    > - Andy for being the VDSO wizard of x86 and in general. He's also the
    > performance monitor of choice and the code in the generic library is
    > heavily influenced by his previous x86 VDSO work.
    >
    > - Thomas for being the dude who has to deal with any form of time(r)
    > nonsense anyway
    >
    > - Vincenzo for being the poor sod who went through all the different
    > architecture implementations in order to unify them. A lot of knowledge
    > gained from VDSO implementation details to the intricacies of taming the
    > build system.
    >
    > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    > ---
    > MAINTAINERS | 12 ++++++++++++
    > 1 file changed, 12 insertions(+)
    >
    > --- a/MAINTAINERS
    > +++ b/MAINTAINERS
    > @@ -6665,6 +6665,18 @@ L: kvm@vger.kernel.org
    > S: Supported
    > F: drivers/uio/uio_pci_generic.c
    >
    > +GENERIC VDSO LIBRARY:
    > +M: Andy Lutomirksy <luto@kernel.org>
    > +M: Thomas Gleixner <tglx@linutronix.de>
    > +M: Vincenzo Frascino <vincenzo.frascino@arm.com>
    > +L: linux-kernel@vger.kernel.org
    > +T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/vdso
    > +S: Maintained
    > +F: lib/vdso
    > +F: kernel/time/vsyscall.c
    > +F: include/vdso
    > +F: include/asm-generic/vdso/vsyscall.h
    > +
    > GENWQE (IBM Generic Workqueue Card)
    > M: Frank Haverkamp <haver@linux.ibm.com>
    > S: Supported
    >

    --
    Regards,
    Vincenzo

    \
     
     \ /
      Last update: 2019-06-24 15:22    [W:4.760 / U:0.104 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site