[lkml]   [2018]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: staging: ion: ION allocation fall back order depends on heap linkage order
On 02/07/2018 07:10 AM, Alexey Skidanov wrote:
> On 02/07/2018 04:58 PM, Laura Abbott wrote:
>> On 02/06/2018 11:05 PM, Alexey Skidanov wrote:
>>>> Yup, you've hit upon a key problem. Having fallbacks be stable
>>>> was always a problem and the recommendation these days is to
>>>> not rely on them. You can specify a heap at a time and fallback
>>>> manually if you want that behavior.
>>>> If you have a proposal to make fallbacks work reliably without
>>>> overly complicating the ABI I'm happy to review it.
>>>> Thanks,
>>>> Laura
>>> I think it's possible to "automate" the "manual fallback" behavior. But
>>> the real issues is using heap id to specify the particular heap object.
>>> Current API (allocation IOCTL) requires to specify the particular heap
>>> object by using heap id. From the other hand, the user space doesn't
>>> control the heaps creation order and heap id assignment. So it may be
>>> tricky, especially when more than one object of the same heap type is
>>> created automatically.
>>> Thanks,
>>> Alexey
>> The query ioctl is designed to get the heap ID information without
>> needing to rely on the linking order or anything else defined in
>> the kernel.
>> Thanks,
>> Laura
> That is true. But if we have 2 *automatically created* heaps of the same
> type, how userspace can distinguish between them?
> Thanks,
> Alexey

The query ioctl also gives the name which should be different
for each heap. It's not ideal but the name/heap type are the best
way to differentiate between heaps without resorting to hard


 \ /
  Last update: 2018-02-07 16:33    [W:0.049 / U:0.672 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site