Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <0be0e378-1601-678c-247a-ba24d111b934@acm.org>
Date:   Fri, 16 Sep 2022 13:01:08 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.12.0
Subject: Re: [PATCH RFC 0/8] Introduce provisioning primitives for thinly
 provisioned storage
Content-Language: en-US
To:     Sarthak Kukreti <sarthakkukreti@chromium.org>,
        Stefan Hajnoczi <stefanha@redhat.com>
Cc:     dm-devel@redhat.com, linux-block@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        Jens Axboe <axboe@kernel.dk>,
        "Michael S . Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Alasdair Kergon <agk@redhat.com>,
        Mike Snitzer <snitzer@kernel.org>,
        Theodore Ts'o <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Bart Van Assche <bvanassche@google.com>,
        Daniil Lunev <dlunev@google.com>,
        Evan Green <evgreen@google.com>,
        Gwendal Grignou <gwendal@google.com>
References: <20220915164826.1396245-1-sarthakkukreti@google.com>
 <YyQTM5PRT2o/GDwy@fedora>
 <CAG9=OMPHZqdDhX=M+ovdg5fa3x4-Q_1r5SWPa8pMTQw0mr5fPg@mail.gmail.com>
From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <CAG9=OMPHZqdDhX=M+ovdg5fa3x4-Q_1r5SWPa8pMTQw0mr5fPg@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

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.