From: "Harris, James R" <james.r.harris@intel.com>
To: Thomas Monjalon <thomas.monjalon@6wind.com>,
"users@dpdk.org" <users@dpdk.org>, "dev@dpdk.org" <dev@dpdk.org>,
"Gonzalez Monroy, Sergio" <sergio.gonzalez.monroy@intel.com>,
"Richardson, Bruce" <bruce.richardson@intel.com>
Cc: "Verkamp, Daniel" <daniel.verkamp@intel.com>
Subject: Re: [dpdk-users] [dpdk-dev] rte_zmalloc() returning non-zeroed memory on FreeBSD
Date: Mon, 15 Aug 2016 17:23:27 +0000 [thread overview]
Message-ID: <A35C21583F92CE4D8ADBF9D61694E910216BF49B@FMSMSX105.amr.corp.intel.com> (raw)
In-Reply-To: <1549431.MJntLMElOg@xps13>
> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Thomas Monjalon
> Sent: Thursday, August 11, 2016 12:05 AM
> To: users@dpdk.org; dev@dpdk.org; Gonzalez Monroy, Sergio; Richardson,
> Bruce
> Cc: Verkamp, Daniel
> Subject: Re: [dpdk-dev] [dpdk-users] rte_zmalloc() returning non-zeroed
> memory on FreeBSD
>
> Hi,
>
> 2016-08-10 23:30, Verkamp, Daniel:
> > It seems that with DPDK 16.07, rte_zmalloc() and related functions no
> > longer return zeroed memory reliably on FreeBSD.
> >
> > I notice that commit b78c9175118f7d61022ddc5c62ce54a1bd73cea5 ("mem:
> do
> > not zero out memory on zmalloc") removed the explicit memset() that
> used
> > to ensure the buffer was zeroed; its log message says:
> >
> > "Zeroing out memory on rte_zmalloc_socket is not required anymore since
> > all allocated memory is already zeroed."
>
> On Linux, the memory is zeroed by the kernel.
> Then the zero value is maintained in the rte_malloc pool by rte_free.
>
> > However, I don't see how this is guaranteed (at least for FreeBSD), and
> > it is not true in practice. I've attached a minimized reproducer program -
> > running it twice in a row fails reliably for me.
> >
> > Is there a missing step in FreeBSD, or is it a more general problem for
> > other platforms?
>
> I guess the initial value from the kernel has been verified only on Linux.
> We could re-add a memset for FreeBSD.
The problem is that the FreeBSD contigmem driver does not re-zero the huge
pages each time they are mmap'd - they are only zeroed when contigmem
initially loads. I will push a patch for this shortly.
next prev parent reply other threads:[~2016-08-15 17:23 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-10 23:30 [dpdk-users] " Verkamp, Daniel
2016-08-10 23:39 ` Verkamp, Daniel
2016-08-11 7:05 ` Thomas Monjalon
2016-08-15 17:23 ` Harris, James R [this message]
[not found] ` <8b8e180e-a996-ef6e-cbf8-23028a194224@intel.com>
2016-08-16 22:54 ` [dpdk-users] [dpdk-dev] " Harris, James R
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