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    SubjectRe: [RFC][PATCH] Cross Memory Attach
    On Wed, 15 Sep 2010 23:46:09 +0900
    Bryan Donlan <bdonlan@gmail.com> wrote:

    > On Wed, Sep 15, 2010 at 19:58, Avi Kivity <avi@redhat.com> wrote:
    >
    > > Instead of those two syscalls, how about a vmfd(pid_t pid, ulong
    > > start, ulong len) system call which returns an file descriptor that
    > > represents a portion of the process address space.  You can then
    > > use preadv() and pwritev() to copy memory, and
    > > io_submit(IO_CMD_PREADV) and io_submit(IO_CMD_PWRITEV) for
    > > asynchronous variants (especially useful with a dma engine, since
    > > that adds latency).
    > >
    > > With some care (and use of mmu_notifiers) you can even mmap() your
    > > vmfd and access remote process memory directly.
    >
    > Rather than introducing a new vmfd() API for this, why not just add
    > implementations for these more efficient operations to the existing
    > /proc/$pid/mem interface?

    Perhaps I'm misunderstanding something here, but
    accessing /proc/$pid/mem requires ptracing the target process.
    We can't really have all these MPI processes ptraceing each other
    just to send/receive a message....

    Regards,

    Chris
    --
    cyeoh@au.ibm.com
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