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: Sun, 19 Jan 2020 11:52:55 +0800 Message-ID: <7c6bb315-1ffc-665d-ff5e-e5e440f3e609@linux.intel.com> (raw) In-Reply-To: <s5ho8v249rk.wl-tiwai@suse.de> On 2020/1/17 下午7:12, Takashi Iwai wrote: > On Fri, 17 Jan 2020 11:43:24 +0100, > Keyon Jie wrote: >> >> >> >> 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)); > > Yes, passing buffer_size_min for the preallocation sounds already > bad. The default value should be sufficient for usual operations, not > the cost-cutting minimum. Otherwise there is no merit of > preallocation. > > Alternatively, we may pass 0 there, indicating no limitation, too. > But, this would need a bit other adjustment, e.g. snd_pcm_hardware > should have lower buffer_bytes_max. Thank you Takashi, then let's follow it to pre-allocate with caps->buffer_size_max, as we don't specify any limitations in snd_pcm_hardware today, we want to leave it configurable to each specific topology file for different machines. 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
next prev parent 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 2020-01-17 11:12 ` Takashi Iwai 2020-01-19 3:52 ` Keyon Jie [this message] 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=7c6bb315-1ffc-665d-ff5e-e5e440f3e609@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