Re: [PATCH v1 0/3] util/oslib-posix: Support MADV_POPULATE_WRITE for os_mem_prealloc()

[Pankaj Gupta]

> > #1 adds support for MADV_POPULATE_WRITE, #2 cleans up the code to avoid
> > global variables and prepare for concurrency and #3 makes os_mem_prealloc()
> > safe to be called from multiple threads concurrently.
> >
> > Details regarding MADV_POPULATE_WRITE can be found in introducing upstream
> > Linux commit 4ca9b3859dac ("mm/madvise: introduce
> > MADV_POPULATE_(READ|WRITE) to prefault page tables") and in the latest man
> > page patch [1].
> >
> > [1] https://lkml.kernel.org/r/20210712083917.16361-1-david@redhat.com
> >
> > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > Cc: Igor Mammedov <imammedo@redhat.com>
> > Cc: Eduardo Habkost <ehabkost@redhat.com>
> > Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > Cc: Marek Kedzierski <mkedzier@redhat.com>
> > Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
> >
> > David Hildenbrand (3):
> >   util/oslib-posix: Support MADV_POPULATE_WRITE for os_mem_prealloc()
> >   util/oslib-posix: Introduce and use MemsetContext for
> >     touch_all_pages()
> >   util/oslib-posix: Support concurrent os_mem_prealloc() invocation
> >
> >  include/qemu/osdep.h |   7 ++
> >  util/oslib-posix.c   | 167 ++++++++++++++++++++++++++++++-------------
> >  2 files changed, 126 insertions(+), 48 deletions(-)
> >
>
> Nice implementation to avoid wear of memory device for prealloc case

For prealloc case I mean.

> and to avoid touching of
> all the memory and abrupt exit of VM because of lack of memory. Instead better
> way to populate the page tables with madvise.
>
> Plan is to use this infrastructure for virtio-mem, I guess?
>
> For the patches 1 & 3:
> Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com>
>
>
> Thanks,
> Pankaj