From: "Xie, Huawei" <huawei.xie@intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [RFC PATCH 2/2] lib/librte_eal: Remove unnecessary hugepage zero-filling
Date: Wed, 25 Nov 2015 18:24:54 +0000 [thread overview]
Message-ID: <C37D651A908B024F974696C65296B57B4B1B263E@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <20151122225220.1fd15ba8@xeon-e3>
On 11/23/2015 2:52 PM, Stephen Hemminger wrote:
> On Mon, 23 Nov 2015 05:05:21 +0000
> "Xie, Huawei" <huawei.xie@intel.com> wrote:
>
>> On 11/23/2015 12:07 PM, Stephen Hemminger wrote:
>>> On Mon, 23 Nov 2015 03:46:31 +0000
>>> "Xie, Huawei" <huawei.xie@intel.com> wrote:
>>>
>>>>> Why cannot we rely on the kernel zeroing the memory ?
>>>>> If that behavior were to change, then we can zero out the memory
>>>>> ourselves.
>>>> It is undocumented kernel behavior. My opinion is if not a big burden,
>>>> zero out the needed memory ourselves, otherwise resort to this kernel
>>>> behavior.
>>> Really, I think it is more an oversight of missing documentation,
>>> the kernel has always (and will continue) to zero out memory that is given
>>> to a process. If it didn't it would be a massive security hole.
>> Agree. I believe this behavior will not change in future. For the
>> security issue, kernel could also set all bits like to 1. Just wonder if
>> this is best practice and whether there are other user space programs
>> rely on this behavior.
>>
> Glibc almost certainly depends on this, because heap is grown by mmaping addtional
> memory.
Thanks. It is OK, but still don't feel good, :). It is like that we
require the clear_user_page(and other unix, windows equivalent) is
always memset(ptr, 0 , PAGE_SIZE). To me, memset(ptr, 1, PAGE_SIZE)
doesn't make difference.
next prev parent reply other threads:[~2015-11-25 18:25 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-18 3:27 [dpdk-dev] [RFC PATCH 0/2] Reduce DPDK initialization time Zhihong Wang
2015-11-18 3:27 ` [dpdk-dev] [RFC PATCH 1/2] lib/librte_eal: Reduce timer " Zhihong Wang
2015-11-18 3:27 ` [dpdk-dev] [RFC PATCH 2/2] lib/librte_eal: Remove unnecessary hugepage zero-filling Zhihong Wang
2015-11-18 10:39 ` Mcnamara, John
2015-11-18 10:44 ` Wang, Zhihong
2015-11-18 12:07 ` Xie, Huawei
2015-11-18 16:00 ` Stephen Hemminger
2015-11-18 16:13 ` Richardson, Bruce
2015-11-18 19:09 ` Stephen Hemminger
2015-11-19 2:15 ` Wang, Zhihong
2015-11-19 6:04 ` Xie, Huawei
2015-11-19 6:32 ` Wang, Zhihong
2015-11-19 9:18 ` Sergio Gonzalez Monroy
2015-11-23 2:54 ` Xie, Huawei
2015-11-23 10:18 ` Bruce Richardson
2015-11-20 12:15 ` Bruce Richardson
2015-11-19 3:54 ` Wang, Zhihong
2015-11-19 6:09 ` Xie, Huawei
2015-11-19 9:14 ` Sergio Gonzalez Monroy
2015-11-23 3:46 ` Xie, Huawei
2015-11-23 4:07 ` Stephen Hemminger
2015-11-23 5:05 ` Xie, Huawei
2015-11-23 6:52 ` Stephen Hemminger
2015-11-25 18:24 ` Xie, Huawei [this message]
2015-12-24 8:34 ` [dpdk-dev] [RFC PATCH 0/2] Reduce DPDK initialization time Qiu, Michael
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