From: John Hubbard <jhubbard@nvidia.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
<gregkh@linuxfoundation.org>, <surenb@google.com>,
<joaodias@google.com>, LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH] mm: cma: support sysfs
Date: Thu, 4 Feb 2021 16:24:20 -0800 [thread overview]
Message-ID: <87d7ec1f-d892-0491-a2de-3d0feecca647@nvidia.com> (raw)
In-Reply-To: <YByNU4Q7cc7gYwPh@google.com>
On 2/4/21 4:12 PM, Minchan Kim wrote:
...
>>> Then, how to know how often CMA API failed?
>>
>> Why would you even need to know that, *in addition* to knowing specific
>> page allocation numbers that failed? Again, there is no real-world motivation
>> cited yet, just "this is good data". Need more stories and support here.
>
> Let me give an example.
>
> Let' assume we use memory buffer allocation via CMA for bluetooth
> enable of device.
> If user clicks the bluetooth button in the phone but fail to allocate
> the memory from CMA, user will still see bluetooth button gray.
> User would think his touch was not enough powerful so he try clicking
> again and fortunately CMA allocation was successful this time and
> they will see bluetooh button enabled and could listen the music.
>
> Here, product team needs to monitor how often CMA alloc failed so
> if the failure ratio is steadily increased than the bar,
> it means engineers need to go investigation.
>
> Make sense?
>
Yes, except that it raises more questions:
1) Isn't this just standard allocation failure? Don't you already have a way
to track that?
Presumably, having the source code, you can easily deduce that a bluetooth
allocation failure goes directly to a CMA allocation failure, right?
Anyway, even though the above is still a little murky, I expect you're right
that it's good to have *some* indication, somewhere about CMA behavior...
Thinking about this some more, I wonder if this is really /proc/vmstat sort
of data that we're talking about. It seems to fit right in there, yes?
thanks,
--
John Hubbard
NVIDIA
next prev parent reply other threads:[~2021-02-05 0:25 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 15:50 [PATCH] mm: cma: support sysfs Minchan Kim
2021-02-04 8:50 ` John Hubbard
2021-02-04 20:07 ` Minchan Kim
2021-02-04 23:14 ` John Hubbard
2021-02-04 23:43 ` Suren Baghdasaryan
2021-02-04 23:45 ` Suren Baghdasaryan
2021-02-05 0:25 ` John Hubbard
2021-02-05 0:34 ` John Hubbard
2021-02-05 1:44 ` Suren Baghdasaryan
2021-02-05 0:12 ` Minchan Kim
2021-02-05 0:24 ` John Hubbard [this message]
2021-02-05 1:44 ` Minchan Kim
2021-02-05 2:39 ` Suren Baghdasaryan
2021-02-05 2:52 ` John Hubbard
2021-02-05 5:17 ` Minchan Kim
2021-02-05 5:49 ` John Hubbard
2021-02-05 6:24 ` Minchan Kim
2021-02-05 6:41 ` John Hubbard
2021-02-05 16:15 ` Minchan Kim
2021-02-05 20:25 ` John Hubbard
2021-02-05 21:28 ` Minchan Kim
2021-02-05 21:52 ` Suren Baghdasaryan
2021-02-05 21:58 ` John Hubbard
2021-02-05 22:47 ` Minchan Kim
2021-02-06 17:08 ` Pintu Agarwal
2021-02-08 8:39 ` John Hubbard
2021-02-05 21:57 ` John Hubbard
2021-02-05 2:55 ` Matthew Wilcox
2021-02-05 5:22 ` Minchan Kim
2021-02-05 12:12 ` Matthew Wilcox
2021-02-05 16:16 ` Minchan Kim
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