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Petersen" Cc: Theodore Ts'o , lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org Subject: Re: [LSF/MM/BPF TOPIC] Cloud storage optimizations Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: F2C5BC000E X-Stat-Signature: m377odpba6skr45ycy4j6x5bkkjzkwfu X-Rspam-User: X-HE-Tag: 1677814187-678387 X-HE-Meta: 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 QP8aVV0G unEGxzej5/pYb2Z9InH8yx89FSQhqhLHbxdKyogiLhfYVxrxjqsTyKHEZ2UEq4tvjXD6bSUWqo35t9ByOLA/WFqFEkD0g8CXuvCZWSFyuXkLEG5aI+0a5VWh+RDXYMYbZ9WllSj87y7z0CT41Q1Kv7EqwOwZf6vfBwk/q5sDZBmjyCQ+FmV3Is05Z93lomt2lV1gZRNMs40oir1x/mgX0ShiAfqOZ+DTZ9UEkeyuCgb7s3cd5Pn+ZdmWiLb07SB+f0kfu4VGCarHinZg4aXSaHZWsMwdDJ6ha0PjF6ezXNugFO8dA0+lBtcQz4h93txSLlQlc X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 02, 2023 at 09:54:59PM -0500, Martin K. Petersen wrote: > > For example, most cloud storage devices are doing read-ahead to try to > > anticipate read requests from the VM. This can interfere with the > > read-ahead being done by the guest kernel. So being able to tell > > cloud storage device whether a particular read request is stemming > > from a read-ahead or not. > > Indeed. In our experience the hints that work best are the ones which > convey to the storage device why the I/O is being performed. This may be a pretty far-out-there idea, but I think SSD BPF injection has potentially higher payoff than mere hints. The below paper does it in kernel, but imagine doing it on the device! https://dl.acm.org/doi/pdf/10.1145/3458336.3465290