From: Juan Quintela <quintela@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kwolf@redhat.com, aliguori@us.ibm.com, stefanha@gmail.com,
pl@kamp.de, qemu-devel@nongnu.org, owasserm@redhat.com
Subject: Re: [Qemu-devel] [PATCH] migration: initialize RAM to zero
Date: Tue, 09 Apr 2013 13:23:19 +0200 [thread overview]
Message-ID: <87li8sdk2g.fsf@elfo.elfo> (raw)
In-Reply-To: <1365418028-2546-1-git-send-email-pbonzini@redhat.com> (Paolo Bonzini's message of "Mon, 8 Apr 2013 12:47:08 +0200")
Paolo Bonzini <pbonzini@redhat.com> wrote:
> 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).
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Except for the mmap return check and the missing valgrind check, the
patch looks good.
Thanks, Juan.
prev parent reply other threads:[~2013-04-09 11:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-08 10:47 [Qemu-devel] [PATCH] migration: initialize RAM to zero Paolo Bonzini
2013-04-08 14:55 ` Peter Lieven
2013-04-09 8:52 ` Markus Armbruster
2013-04-09 8:56 ` Paolo Bonzini
2013-04-09 11:27 ` Markus Armbruster
2013-04-09 11:23 ` Juan Quintela [this message]
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