From: Keyon Jie <yang.jie@linux.intel.com>
To: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
"Rajwa, Marcin" <marcin.rajwa@linux.intel.com>,
"Jie, Yang" <yang.jie@intel.com>, Takashi Iwai <tiwai@suse.de>
Cc: "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>
Subject: Re: [alsa-devel] [PATCH] ALSA: pcm: fix buffer_bytes max constrained by preallocated bytes issue
Date: Fri, 17 Jan 2020 13:37:16 +0800 [thread overview]
Message-ID: <3374dc7d-e969-5380-581a-f6801a2fe50f@linux.intel.com> (raw)
In-Reply-To: <b6b55180-b846-96e7-4521-7d3b03881d06@linux.intel.com>
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...
Thanks,
~Keyon
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next prev parent reply other threads:[~2020-01-17 5:37 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 4:53 [alsa-devel] [PATCH] ALSA: pcm: fix buffer_bytes max constrained by preallocated bytes issue 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 [this message]
2020-01-17 8:00 ` Takashi Iwai
2020-01-17 10:43 ` Keyon Jie
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
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