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Subject: Re: [PATCH] mm: cma: support sysfs
To:     Suren Baghdasaryan <surenb@google.com>,
        Minchan Kim <minchan@kernel.org>
CC:     Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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From:   John Hubbard <jhubbard@nvidia.com>
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On 2/5/21 1:52 PM, Suren Baghdasaryan wrote:
>>>> I takes your suggestion something like this.
>>>>
>>>> [alloc_range] could be order or range by interval
>>>>
>>>> /sys/kernel/mm/cma/cma-A/[alloc_range]/success
>>>> /sys/kernel/mm/cma/cma-A/[alloc_range]/fail
>>>> ..
>>>> ..
>>>> /sys/kernel/mm/cma/cma-Z/[alloc_range]/success
>>>> /sys/kernel/mm/cma/cma-Z/[alloc_range]/fail
> 
> The interface above seems to me the most useful actually, if by
> [alloc_range] you mean the different allocation orders. This would
> cover Minchan's per-CMA failure tracking and would also allow us to
> understand what kind of allocations are failing and therefore if the
> problem is caused by pinning/fragmentation or by over-utilization.
> 

I agree. That seems about right, now that we've established that
cma areas are a must-have.

thanks,
-- 
John Hubbard
NVIDIA