Alsa-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Keyon Jie <yang.jie@linux.intel.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	"Rajwa, Marcin" <marcin.rajwa@linux.intel.com>
Subject: Re: [alsa-devel] [PATCH] ALSA: pcm: fix buffer_bytes max constrained by preallocated bytes issue
Date: Fri, 17 Jan 2020 18:43:24 +0800
Message-ID: <68e008e2-6796-f893-35ed-d76a2bf92587@linux.intel.com> (raw)
In-Reply-To: <s5hzhemo6ku.wl-tiwai@suse.de>



On 2020/1/17 下午4:00, Takashi Iwai wrote:
> On Fri, 17 Jan 2020 06:37:16 +0100,
> Keyon Jie wrote:
>>
>> On 2020/1/17 上午1:40, Pierre-Louis Bossart wrote:
>>>
>>>>>>> So, do you suggest not doing preallocation(or calling it with 0
>>>>>>> size) for all
>>>>>>> driver with TYPE_SG? I am fine if this is the recommended
>>>>>>> method, I can try
>>>>>>> this on SOF I2S platform to see if it can work as we required
>>>>>>> for very large
>>>>>>> buffer size.
>>>>>
>>>>> Keyon, for the rest of us to follow this patch, would you mind
>>>>> clarifying what drives the need for a 'very large buffer size',
>>>>> and what order of magnitude this very large size would be.
>>>>>
>>>>> FWIW, we've measured consistently on different Windows/Linux
>>>>> platforms, maybe 10 years ago, that once you reach a buffer of 1s
>>>>> (384 kB) the benefits from increasing that buffer size further are
>>>>> marginal in terms of power consumption, and generate all kinds of
>>>>> issues with volume updates and deferred routing changes.
>>>>>
>>>> We need bigger buffer on host side to compensate the wake up time
>>>> from d0ix to d0 which takes ~2 seconds on my setup. So, wiith
>>>> smaller buffer sizes like < 2 seconds we overwrite data since FW
>>>> keeps copping while host doesn't read until its up and running
>>>> again.
>>>
>>> Right, that's a valid case, but that's 256 kB, not 'very large' or
>>> likely to ever trigger an OOM case.
>>
>> For S24_LE, it is 512KB, the point is that if we can't re-allocate
>> buffer at hw_params() stage, then we need follow a BKM that we have to
>> preallocate the largest DMA buffer that we claim to support at
>> pcm_new(), I think this is actually another kind of wast with these
>> largest pinned buffer that can't be swapped out...
> 
> Well, that's the case you'd need a larger preallocation.
> I guess many distros already set it to a higher value for PulseAudio.
> The default 64kB is just from historical and compatibility reason, and
> we may extend it to 1MB or so now.

In SOF driver, we don't use kernel config item like 
CONFIG_SND_HDA_PREALLOC_SIZE for HDA, the code for it is:

	snd_pcm_lib_preallocate_pages(pcm->streams[stream].substream,
				      SNDRV_DMA_TYPE_DEV_SG, sdev->dev,
				le32_to_cpu(caps->buffer_size_min),
				le32_to_cpu(caps->buffer_size_max));

So the preallocated size is configured via topology file, that is 
caps->buffer_size_min, no chance for PulseAudio to reconfigure it.

So, it looks like we have to change it to this if we don't change the 
ALSA core:

	snd_pcm_lib_preallocate_pages(pcm->streams[stream].substream,
				      SNDRV_DMA_TYPE_DEV_SG, sdev->dev,
-				le32_to_cpu(caps->buffer_size_min),
+				le32_to_cpu(caps->buffer_size_max),
				le32_to_cpu(caps->buffer_size_max));


Thanks,
~Keyon

> 
> 
> Takashi
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@alsa-project.org
> https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> 
_______________________________________________
Alsa-devel mailing list
Alsa-devel@alsa-project.org
https://mailman.alsa-project.org/mailman/listinfo/alsa-devel

  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16  4:53 Keyon Jie
2020-01-16  7:15 ` Takashi Iwai
2020-01-16  9:50   ` Keyon Jie
2020-01-16 10:27     ` Takashi Iwai
2020-01-16 11:25       ` Keyon Jie
2020-01-16 11:50         ` Takashi Iwai
2020-01-16 14:14           ` Jie, Yang
2020-01-16 15:31             ` Jie, Yang
2020-01-16 16:07               ` Takashi Iwai
2020-01-16 16:39               ` Pierre-Louis Bossart
2020-01-16 17:25                 ` Rajwa, Marcin
2020-01-16 17:40                   ` Pierre-Louis Bossart
2020-01-16 20:37                     ` Takashi Iwai
2020-01-17  5:30                       ` Keyon Jie
2020-01-17  7:57                         ` Takashi Iwai
2020-01-17 10:13                           ` Keyon Jie
2020-01-17 10:30                             ` Takashi Iwai
2020-01-17 10:56                               ` Keyon Jie
2020-01-17 11:15                                 ` Takashi Iwai
2020-01-17  5:37                     ` Keyon Jie
2020-01-17  8:00                       ` Takashi Iwai
2020-01-17 10:43                         ` Keyon Jie [this message]
2020-01-17 11:12                           ` Takashi Iwai
2020-01-19  3:52                             ` Keyon Jie
2020-01-19  7:09                               ` Takashi Iwai
2020-01-19  8:11                                 ` Keyon Jie
2020-01-19  9:04                                   ` Takashi Iwai
2020-01-19 10:14                                     ` Keyon Jie
2020-01-19 10:43                                       ` Takashi Iwai
2020-01-20  2:23                                         ` Keyon Jie
2020-01-16 15:45             ` Takashi Iwai

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=68e008e2-6796-f893-35ed-d76a2bf92587@linux.intel.com \
    --to=yang.jie@linux.intel.com \
    --cc=alsa-devel@alsa-project.org \
    --cc=marcin.rajwa@linux.intel.com \
    --cc=pierre-louis.bossart@linux.intel.com \
    --cc=tiwai@suse.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Alsa-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/alsa-devel/0 alsa-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 alsa-devel alsa-devel/ https://lore.kernel.org/alsa-devel \
		alsa-devel@alsa-project.org
	public-inbox-index alsa-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.alsa-project.alsa-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git