linux-ext4 - Re: [PATCH RFC 0/8] Introduce provisioning primitives for thinly provisioned storage

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Date:   Fri, 16 Sep 2022 13:01:08 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Sarthak Kukreti <sarthakkukreti@...omium.org>,
        Stefan Hajnoczi <stefanha@...hat.com>
Cc:     dm-devel@...hat.com, linux-block@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Jens Axboe <axboe@...nel.dk>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...nel.org>,
        Theodore Ts'o <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Bart Van Assche <bvanassche@...gle.com>,
        Daniil Lunev <dlunev@...gle.com>,
        Evan Green <evgreen@...gle.com>,
        Gwendal Grignou <gwendal@...gle.com>
Subject: Re: [PATCH RFC 0/8] Introduce provisioning primitives for thinly
 provisioned storage

On 9/16/22 11:48, Sarthak Kukreti wrote:
> Yes. On ChromiumOS, we regularly deal with storage devices that don't
> support WRITE_ZEROES or that need to have it disabled, via a quirk,
> due to a bug in the vendor's implementation. Using WRITE_ZEROES for
> allocation makes the allocation path quite slow for such devices (not
> to mention the effect on storage lifetime), so having a separate
> provisioning construct is very appealing. Even for devices that do
> support an efficient WRITE_ZEROES implementation but don't support
> logical provisioning per-se, I suppose that the allocation path might
> be a bit faster (the device driver's request queue would report
> 'max_provision_sectors'=0 and the request would be short circuited
> there) although I haven't benchmarked the difference.

Some background information about why ChromiumOS uses thin provisioning 
instead of a single filesystem across the entire storage device would be 
welcome. Although UFS devices support thin provisioning I am not aware 
of any use cases in Android that would benefit from UFS thin 
provisioning support.

Thanks,

Bart.