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
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