RE: [PATCH 0/8] memblock: introduce memsize showing reserved memory

Jaewon Kim posted 8 patches 4 years, 2 months ago
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RE: [PATCH 0/8] memblock: introduce memsize showing reserved memory
Posted by Jaewon Kim 4 years, 2 months ago
>> > 
>> >--------- Original Message ---------
>> >Sender : Mike Rapoport <rppt@kernel.org>
>> >Date : 2022-03-27 16:40 (GMT+9)
>> >Title : Re: [PATCH 0/8] memblock: introduce memsize showing reserved memory
>> > 
>> > 
>> >I'm still not following. The reserved region sizes are available in the
>> >existing memblock debugfs.
>> >Why the names are important? What is the value of having names for *some*
>> >of the reserved regions?
>> 
>> Hi
>> 
>> There are many memory regions in memblock debugfs memory/reserved, and some might
>> be splited or merged with other region. Among regions in debugfs, we can't find 
>> the one we defined in device tree. Especially it is difficult to find the region we
>> described size only without start address.
>> 
>> On mobile environment, memory is used by not only CPU but also GPU, Camera, Secure
>> world, Audio, ETC. To support them, there are many reserved regions described in
>> device tree. So the name is quite important to recognize a region. And with thename
>> we can compare reserved memory map with other map.
>
>You still didn't describe your use case. What is the problem your patches
>are trying to solve? Why is it important to know what is the use of particular
>reserved region? 
>
>You propose complex mechanism that seems to fit very particular scenario
>and sprinkle some calls to this mechanism at random places because you need
>to "compare reserved memory map with other map".
>
>Does not sound convincing to me, sorry.

As I said serveral times, I want a simple knob showing all reserved memory status.
The current debugfs, device tree do not show all those information I want. I think you also know that.
 i.e. late freed pages, splited or merged memblock, address defined at boot time, kernel size, ETC. 

Anyway I think I touched too many points to do this. Let me drop this.

>
>> Thank you
>> Jaewon Kim
>
>-- 
>Sincerely yours,
>Mike.
>
Re: [PATCH 0/8] memblock: introduce memsize showing reserved memory
Posted by Mike Rapoport 4 years, 2 months ago
Hi,

On Tue, Mar 29, 2022 at 11:46:20AM +0900, Jaewon Kim wrote:
> >> > 
> >> >I'm still not following. The reserved region sizes are available in the
> >> >existing memblock debugfs.
> >> >Why the names are important? What is the value of having names for *some*
> >> >of the reserved regions?
> >> 
> >> Hi
> >> 
> >> There are many memory regions in memblock debugfs memory/reserved, and some might
> >> be splited or merged with other region. Among regions in debugfs, we can't find 
> >> the one we defined in device tree. Especially it is difficult to find the region we
> >> described size only without start address.
> >> 
> >> On mobile environment, memory is used by not only CPU but also GPU, Camera, Secure
> >> world, Audio, ETC. To support them, there are many reserved regions described in
> >> device tree. So the name is quite important to recognize a region. And with thename
> >> we can compare reserved memory map with other map.
> >
> >You still didn't describe your use case. What is the problem your patches
> >are trying to solve? Why is it important to know what is the use of particular
> >reserved region? 
> >
> >You propose complex mechanism that seems to fit very particular scenario
> >and sprinkle some calls to this mechanism at random places because you need
> >to "compare reserved memory map with other map".
> >
> >Does not sound convincing to me, sorry.
> 
> As I said serveral times, I want a simple knob showing all reserved
> memory status.  The current debugfs, device tree do not show all those
> information I want. I think you also know that.  i.e. late freed pages,
> splited or merged memblock, address defined at boot time, kernel size,
> ETC. 

I know that there is not much information about reserved memory exposed and
I understand *what* are you trying to achieve. But you never provided
details about *why* you want this information exposed.

I don't mind providing more visibility into reserved memory attributes in
general, but I'd like to see something way more simple and localized.

-- 
Sincerely yours,
Mike.
RE: [PATCH 0/8] memblock: introduce memsize showing reserved memory
Posted by Jaewon Kim 4 years, 2 months ago
>Hi,
>
>On Tue, Mar 29, 2022 at 11:46:20AM +0900, Jaewon Kim wrote:
>> >> > 
>> >> >I'm still not following. The reserved region sizes are available in the
>> >> >existing memblock debugfs.
>> >> >Why the names are important? What is the value of having names for *some*
>> >> >of the reserved regions?
>> >> 
>> >> Hi
>> >> 
>> >> There are many memory regions in memblock debugfs memory/reserved, and some might
>> >> be splited or merged with other region. Among regions in debugfs, we can't find 
>> >> the one we defined in device tree. Especially it is difficult to find the region we
>> >> described size only without start address.
>> >> 
>> >> On mobile environment, memory is used by not only CPU but also GPU, Camera, Secure
>> >> world, Audio, ETC. To support them, there are many reserved regions described in
>> >> device tree. So the name is quite important to recognize a region. And with thename
>> >> we can compare reserved memory map with other map.
>> >
>> >You still didn't describe your use case. What is the problem your patches
>> >are trying to solve? Why is it important to know what is the use of particular
>> >reserved region? 
>> >
>> >You propose complex mechanism that seems to fit very particular scenario
>> >and sprinkle some calls to this mechanism at random places because you need
>> >to "compare reserved memory map with other map".
>> >
>> >Does not sound convincing to me, sorry.
>> 
>> As I said serveral times, I want a simple knob showing all reserved
>> memory status.  The current debugfs, device tree do not show all those
>> information I want. I think you also know that.  i.e. late freed pages,
>> splited or merged memblock, address defined at boot time, kernel size,
>> ETC. 
>
>I know that there is not much information about reserved memory exposed and
>I understand *what* are you trying to achieve. But you never provided
>details about *why* you want this information exposed.
>
>I don't mind providing more visibility into reserved memory attributes in
>general, but I'd like to see something way more simple and localized.
>

I think the "what" is same as "why".
I want to look at all reservced memory status simply in a knob.

I also want to make in more simple and localized way, but there seems be
several ways to change reserved memory such as cmdline way, freeing after
boot, etc. I wanted to cover all those things.

That's OK. I hope someone later to try this again to show all the info.

>-- 
>Sincerely yours,
>Mike.