From: Takashi Iwai <tiwai@suse.de>
To: Keyon Jie <yang.jie@linux.intel.com>
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 09:00:49 +0100 [thread overview]
Message-ID: <s5hzhemo6ku.wl-tiwai@suse.de> (raw)
In-Reply-To: <3374dc7d-e969-5380-581a-f6801a2fe50f@linux.intel.com>
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.
Takashi
_______________________________________________
Alsa-devel mailing list
Alsa-devel@alsa-project.org
https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
next prev parent reply other threads:[~2020-01-17 8:01 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
2020-01-17 8:00 ` Takashi Iwai [this message]
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
Reply instructions:
You may reply publicly 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=s5hzhemo6ku.wl-tiwai@suse.de \
--to=tiwai@suse.de \
--cc=alsa-devel@alsa-project.org \
--cc=marcin.rajwa@linux.intel.com \
--cc=pierre-louis.bossart@linux.intel.com \
--cc=yang.jie@linux.intel.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).