[dpdk-dev] [PATCH] mem: warn if address hint is not respected
Jonas Pfefferle
pepperjo at japf.ch
Wed Jan 3 10:22:22 CET 2018
Hi Xueming,
Correct --base-virtaddr was introduced for that purpose. There are
multiple reasons why the address layout of the secondary process might
look different: reasons you mentioned in 2), ASLR etc. I believe there
is no way to avoid this in real world use cases. The reason for this
particular patch is that the address hint (--base-virtaddr) is
sometimes not respected and the kernel falls back to just reserving
any address it can find to satisfy the mapping (see discussion on the
patch), i.e. effectively rendering --base-virtaddr useless.
Regards,
Jonas (new email address)
On Tue, 26 Dec 2017 15:56:10 +0000
"Xueming(Steven) Li" <xuemingl at mellanox.com> wrote:
> Hi Jonas,
>
> Seems you are trying to use --base-virtaddr to resolve address
>conflicts
> in secondary, I'm wondering how this happened and how to avoid it:
> 1. what's your hugepage side? Hugepage mmap is size aligned, maybe
>1G works?
> 2. is there more libs loaded in secondary process or memory usage
>before
> EAL init?
> 3. Since address allocated in one direction, I'm thinking to reserve
>a
> larger "hop" address space as MAP_ANONYMOUS, allocate hugepage, then
>release
> "hop". That essentially reserve an address space big enough for
>secondary,
> and most important the hop size is easy to estimate than
>--base-virtaddr.
>
> Thanks,
> Xueming(Steven)
>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Jonas
>>Pfefferle1
>> Sent: Wednesday, November 8, 2017 7:52 PM
>> To: Burakov, Anatoly <anatoly.burakov at intel.com>
>> Cc: dev at dpdk.org; jianfeng.tan at intel.com; Thomas Monjalon
>> <thomas at monjalon.net>
>> Subject: Re: [dpdk-dev] [PATCH] mem: warn if address hint is not
>>respected
>>
>> "Burakov, Anatoly" <anatoly.burakov at intel.com> wrote on 11/07/2017
>> 02:54:24
>> PM:
>>
>> > From: "Burakov, Anatoly" <anatoly.burakov at intel.com>
>> > To: Thomas Monjalon <thomas at monjalon.net>
>> > Cc: dev at dpdk.org, Jonas Pfefferle <jpf at zurich.ibm.com>,
>> jianfeng.tan at intel.com
>> > Date: 11/07/2017 02:54 PM
>> > Subject: Re: [dpdk-dev] [PATCH] mem: warn if address hint is not
>> respected
>> >
>> > On 06-Nov-17 8:26 PM, Thomas Monjalon wrote:
>> > > 31/10/2017 10:08, Jonas Pfefferle:
>> > >> Print a warning if the --base-virtaddr hint is not respected
>>since
>> > >> this might lead to problems when mapping memory in the
>>secondary
>> > >> process.
>> > >>
>> > >> Signed-off-by: Jonas Pfefferle <jpf at zurich.ibm.com>
>> > >
>> > > Anatoly, please review this patch.
>> > > It does not seem to fix something, so it is candidate for 18.02.
>> > >
>> >
>> > For some reason my Thunderbird ate the original email, so i'll
>>reply
>> > to this one.
>> >
>> > One nitpick would be that we're calling get_virtual_area many
>>times
>> > and it would probably be a good idea to make pagesize static and
>>call
>> > sysconf only once. Otherwise,
>>
>> We should address this in a separate patch and introduce a pagesize
>> function for everyone to use. sysconf is used like this all over the
>>place.
>>
>> >
>> > Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>
>> >
>> > --
>> > Thanks,
>> > Anatoly
>> >
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