From: Markus Armbruster <armbru@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kwolf@redhat.com, aliguori@us.ibm.com, quintela@redhat.com,
pl@kamp.de, qemu-devel@nongnu.org, owasserm@redhat.com,
stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH v3] migration: initialize RAM to zero
Date: Wed, 10 Apr 2013 10:03:46 +0200 [thread overview]
Message-ID: <87k3oavml9.fsf@blackfin.pond.sub.org> (raw)
In-Reply-To: <1365522223-20153-1-git-send-email-pbonzini@redhat.com> (Paolo Bonzini's message of "Tue, 9 Apr 2013 17:43:43 +0200")
Paolo Bonzini <pbonzini@redhat.com> writes:
> Using qemu_memalign only leaves the RAM zero by chance, because libc
> will usually use mmap to satisfy our huge requests. But memory will
> not be zero when using MALLOC_PERTURB_ with a nonzero value. In the
> case of incoming migration, this breaks a recently-introduced
> invariant (commit f1c7279, migration: do not sent zero pages in
> bulk stage, 2013-03-26).
>
> To fix this, use mmap ourselves to get a well-aligned, always zero
> block for the RAM. Mmap-ed memory is easy to "trim" at the sides.
>
> This also removes the need to do something special on valgrind
> (see commit c2a8238a, Support running QEMU on Valgrind, 2011-10-31),
> thus effectively reverts that patch.
>
> Reviewed-by: Juan Quintela <quintela@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
next prev parent reply other threads:[~2013-04-10 8:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-09 15:43 [Qemu-devel] [PATCH v3] migration: initialize RAM to zero Paolo Bonzini
2013-04-10 8:03 ` Markus Armbruster [this message]
2013-04-22 18:38 ` Anthony Liguori
2013-05-13 5:38 ` [Qemu-devel] regression: (was Re: [PATCH v3] migration: initialize RAM to zero) Amos Kong
2013-05-13 13:50 ` [Qemu-devel] [PATCH v3] migration: initialize RAM to zero Anthony Liguori
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