Re: [Qemu-devel] [PULL 09/27] migration: calculate vCPU blocktime on dst side

[Alexey Perevalov]

On 01/16/2018 08:43 PM, Dr. David Alan Gilbert wrote:
> * Max Reitz (address@hidden) wrote:
> > On 2018-01-15 12:52, Juan Quintela wrote:
> > > From: Alexey Perevalov <address@hidden>
> > >
> > > This patch provides blocktime calculation per vCPU,
> > > as a summary and as a overlapped value for all vCPUs.
> > >
> > > This approach was suggested by Peter Xu, as an improvements of
> > > previous approch where QEMU kept tree with faulted page address and cpus bitmask
> > > in it. Now QEMU is keeping array with faulted page address as value and vCPU
> > > as index. It helps to find proper vCPU at UFFD_COPY time. Also it keeps
> > > list for blocktime per vCPU (could be traced with page_fault_addr)
> > >
> > > Blocktime will not calculated if postcopy_blocktime field of
> > > MigrationIncomingState wasn't initialized.
> > >
> > > Signed-off-by: Alexey Perevalov <address@hidden>
> > > Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> > > Reviewed-by: Juan Quintela <address@hidden>
> > > Signed-off-by: Juan Quintela <address@hidden>
> > > ---
> > >   migration/postcopy-ram.c | 143 ++++++++++++++++++++++++++++++++++++++++++++++-
> > >   migration/trace-events   |   5 +-
> > >   2 files changed, 146 insertions(+), 2 deletions(-)
> > For me, this breaks compilation with clang -m32:
> >
> >    LINK    x86_64-softmmu/qemu-system-x86_64
> > ../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_begin':
> > /home/maxx/projects/qemu/migration/postcopy-ram.c:599: undefined
> > reference to `__atomic_exchange_8'
> > /home/maxx/projects/qemu/migration/postcopy-ram.c:600: undefined
> > reference to `__atomic_exchange_8'
> > /home/maxx/projects/qemu/migration/postcopy-ram.c:609: undefined
> > reference to `__atomic_exchange_8'
> > ../migration/postcopy-ram.o: In function `mark_postcopy_blocktime_end':
> > /home/maxx/projects/qemu/migration/postcopy-ram.c:665: undefined
> > reference to `__atomic_fetch_add_8'
> > /home/maxx/projects/qemu/migration/postcopy-ram.c:686: undefined
> > reference to `__atomic_fetch_add_8'
> >
> > Am I doing something wrong?
> Hmm I also see that with clang on 32bit (gcc is fine);
> the problem is the postcopy blocktime stuff is doing some 64bit
> atomics, which you can never be sure 32bit will support.
>
> Dave
I didn't check clang build, ok, I'll check it.

> > Max
>
>
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK

--
Best regards,
Alexey Perevalov,
phone: +7 (495) 797 25 00 ext 3969
e-mail: address@hidden <mailto:address@hidden>

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