[dpdk-users] [dpdk-dev] rte_zmalloc() returning non-zeroed memory on FreeBSD

Sergio Gonzalez Monroy sergio.gonzalez.monroy at intel.com
Tue Aug 16 09:36:43 CEST 2016

On 15/08/2016 18:23, Harris, James R wrote:
>> -----Original Message-----
>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Thomas Monjalon
>> Sent: Thursday, August 11, 2016 12:05 AM
>> To: users at dpdk.org; dev at 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.

So that is the case where we run the app more than once, right?
I missed that, I only ran it once.


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